Antibodies and compositions against p2x receptors and uses thereof

Abstract

Antibodies and compositions against P2X receptors and uses thereof are provided. Methods for treating pain and other conditions using the same are also provided.

Description

Attorney Docket No. ITL-013WO ANTIBODIES AND COMPOSITIONS AGAINST P2X RECEPTORS AND USES THEREOF CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Patent Application No.63 / 683,576, filed August 15, 2024, the disclosure of which is hereby incorporated by reference in its entirety for all purposes. GOVERNMENT SUPPORT

[0002] This invention was made with government support under NIH Grant No. GM096500. The government has certain rights in the invention. BACKGROUND:

[0003] Acute and chronic pain resulting from injury, surgery, or disease afflicts >100 million Americans each year, having a severe impact on physical and mental health, productivity, and quality of life. Chronic pain is often caused by a hypersensitive response to stimuli (hyperalgesia) or an inappropriate reaction to innocuous stimuli (allodynia) (reviewed in (Institute of Medicine (2011). Relieving Pain in America: A Blueprint for Transforming Prevention, Care, Education, and Research, National Academy of Sciences; Nightingale, S. (2012). The neuropathic pain market. Nat Rev Drug Discov 11, 101-102). Neuropathic pain (resulting from damage to the somatosensory system) can be caused by peripheral nerve damage, tumor growths, and spinal misalignment (e.g., back pain), whereas inflammatory pain (associated with activation of the immune system) can be caused by rheumatoid arthritis, brain swelling, and tissue damage / repair. However, the etiology of chronic pain is often difficult to delineate, rendering it particularly challenging to treat. For example, irritable bowel syndrome (IBS, affecting up to 15% of adult Americans) and fibromyalgia (affecting more than 6 million patients in the US) are chronic, neuropathic pain conditions that have no well-defined cause. Arthritic conditions, such as osteoarthritis and rheumatoid arthritis, are characterized by joint inflammation and pain, and affect 47.3 million Americans (22% of the population).

[0004] To date, most treatments for pain have been small molecule compounds that block the activity of select ion channels or other pain receptors, such as the GABA analogs gabapentin and pregabalin (Lyrica, Pfizer, with $3.7 billion in sales in 2011), which block the α2δ-1 subunit of voltage-dependent calcium channels in neuronal synapses (Eroglu, C., et al. (2009). Gabapentin receptor alpha2delta-1 is a neuronal thrombospondin receptor responsible -1- IPTS / 200096106.1Attorney Docket No. ITL-013WO for excitatory CNS synaptogenesis. Cell 139, 380-392). However, for many patients, existing treatment options provide inadequate relief because of the shortcomings of available therapeutics and dose-limiting side effects. For example, conventional opioid-based drugs (e.g., morphine, codeine, oxycodone) have been used as analgesics for centuries, but their use is associated with gastrointestinal side effects, nausea and vomiting, addiction, and central nervous system side effects, leading to inadequate pain relief, poor patient quality of life, and discontinuation of therapy (reviewed in Ahlbeck, K. (2011). Opioids: a two-faced Janus. Curr Med Res Opin 27, 439-448).. Aspirin and acetaminophen are adequate for treatment of mild, but not severe, pain. Other pain treatments include COX-2 inhibitors such as Vioxx, Celebrex, and Bextra, most of which have now been withdrawn from the market due to off- target effects that increase the risk of heart attacks and strokes(Marnett, L. J. (2009). The COXIB experience: a look in the rearview mirror. Annu Rev Pharmacol Toxicol 49, 265- 290). Pain management is still only achieved in one in four pain patients (Nightingale, S. (2012). The neuropathic pain market. Nat Rev Drug Discov 11, 101-102), leaving significant space in the market for new entrants, particularly those with novel mechanisms of action.

[0005] Accordingly, there is a need for further pain treatments. The present subject matter fulfills other needs as well as will be discussed herein. SUMMARY OF THE INVENTION

[0006] Disclosed herein, in various embodiments, is an isolated antibody or antigen- binding fragment thereof that binds to a P2X3 protein, a P2X2 protein, or a P2X2 / P2X3 heterodimer protein. In some embodiments, the isolated antibody or antigen binding fragment binds to a P2X3 protein, a P2X2 protein, or a P2X2 / P2X3 heterodimer protein that is properly folded. In some embodiments, the isolated antibody or antigen binding fragment binds to a P2X3 protein, a P2X2 protein, or a P2X2 / P2X3 heterodimer protein that is in a cell membrane. In some embodiments, the isolated antibody or antigen binding fragment binds to a P2X3 protein, a P2X2 protein, or a P2X2 / P2X3 heterodimer protein that is in a cell membrane in an intact cell. In some embodiments, erein the isolated antibody or antigen binding fragment inhibits the function of the P2X3 protein, the P2X2 protein, or the P2X2 / P2X3 heterodimer protein. In some embodiments, the isolated antibody or antigen binding fragment inhibits the ion transport facilitated by the P2X3 protein, the P2X2 protein, or the P2X2 / P2X3 heterodimer. -2- IPTS / 200096106.1Attorney Docket No. ITL-013WO

[0007] In some embodiments, the isolated antibody or antigen binding fragment comprises a heavy chain CDR or an antigen binding fragment thereof described in Table 4. In some embodiments, the isolated antibody or antigen binding fragment comprises a light chain CDR or an antigen binding fragment thereof described in Table 4. In some embodiments, the isolated antibody or antigen binding fragment comprises one or more amino acid sequences of SEQ ID NOs: 1-146 and the amino acid sequences of DND, WND, DNT, SNN, SND, DST, QNN, SSD, and NND, an antigen binding fragment thereof, or a human IgG variant thereof.

[0008] In some embodiments, the antibody or antigen binding fragment comprises: (a) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 3, an HCDR2 amino acid sequence set forth in SEQ ID NO: 4, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 5, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 6, an LCDR2 amino acid sequence of DND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 7; (b) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 15, an HCDR2 amino acid sequence set forth in SEQ ID NO: 16, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 17, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 18, an LCDR2 amino acid sequence of WND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 19; (c) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 27, an HCDR2 amino acid sequence set forth in SEQ ID NO: 28, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 29, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 30, an LCDR2 amino acid sequence of DNT, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 31; (d) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 40, an HCDR2 amino acid sequence set forth in SEQ ID NO: 41, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 42, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 43, an LCDR2 amino acid sequence of SNN, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 44; (e) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 53, an HCDR2 amino acid sequence set forth in SEQ ID NO: 41, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 54, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 55, an LCDR2 amino acid sequence of SND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 56; (f) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 53, an HCDR2 amino acid sequence set forth in SEQ ID NO: 41, and an HCDR3 amino acid -3- IPTS / 200096106.1Attorney Docket No. ITL-013WO sequence set forth in SEQ ID NO: 54, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 64, an LCDR2 amino acid sequence of SND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 65; (g) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 69, an HCDR2 amino acid sequence set forth in SEQ ID NO: 70, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 71, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 72, an LCDR2 amino acid sequence of DST, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 73; (h) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 83, an HCDR2 amino acid sequence set forth in SEQ ID NO: 84, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 85, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 86, an LCDR2 amino acid sequence of QNN, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 87; (i) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 95, an HCDR2 amino acid sequence set forth in SEQ ID NO: 96, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 97, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 98, an LCDR2 amino acid sequence of SND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 99; (j) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 106, an HCDR2 amino acid sequence set forth in SEQ ID NO: 107, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 108, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 109, an LCDR2 amino acid sequence of SND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 110; (k) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 95, an HCDR2 amino acid sequence set forth in SEQ ID NO: 96, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 108, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 98, an LCDR2 amino acid sequence of SSD, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 117; (l) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 106, an HCDR2 amino acid sequence set forth in SEQ ID NO: 107, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 108, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 121, an LCDR2 amino acid sequence of DNT, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 122; (m) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 106, an HCDR2 amino acid sequence set forth in SEQ ID NO: 107, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 108, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 126, an LCDR2 amino acid sequence of SND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 110; (n) a VH comprising an HCDR1 amino acid -4- IPTS / 200096106.1Attorney Docket No. ITL-013WO sequence set forth in SEQ ID NO: 95, an HCDR2 amino acid sequence set forth in SEQ ID NO: 96, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 130, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 98, an LCDR2 amino acid sequence of SND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 99; (o) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 95, an HCDR2 amino acid sequence set forth in SEQ ID NO: 134, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 130, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 135, an LCDR2 amino acid sequence of NND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 136; (p) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 106, an HCDR2 amino acid sequence set forth in SEQ ID NO: 107, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 130, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 126, an LCDR2 amino acid sequence of SND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 142; (q) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 69, an HCDR2 amino acid sequence set forth in SEQ ID NO: 70, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 71, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 144, an LCDR2 amino acid sequence of DST, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 73; or (r) a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 145, an LCDR2 amino acid sequence of SND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 146.

[0009] In some embodiments, the antibody or antigen binding fragment comprises: (a) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 8, an HCDR2 amino acid sequence set forth in SEQ ID NO: 9, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 10, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 11, an LCDR2 amino acid sequence set forth in SEQ ID NO: 12, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 7; (b) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 20, an HCDR2 amino acid sequence set forth in SEQ ID NO: 21, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 22, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 23, an LCDR2 amino acid sequence set forth in SEQ ID NO: 24, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 19; (c) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 32, an HCDR2 amino acid sequence set forth in SEQ ID NO: 33, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 34, and a VL comprising an LCDR1 -5- IPTS / 200096106.1Attorney Docket No. ITL-013WO amino acid sequence set forth in SEQ ID NO: 35, an LCDR2 amino acid sequence set forth in SEQ ID NO: 36, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 31; (d) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 45, an HCDR2 amino acid sequence set forth in SEQ ID NO: 46, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 47, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 48, an LCDR2 amino acid sequence set forth in SEQ ID NO: 49, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 44; (e) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 57, an HCDR2 amino acid sequence set forth in SEQ ID NO: 58, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 59, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 60, an LCDR2 amino acid sequence set forth in SEQ ID NO: 61, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 56; (f) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 57, an HCDR2 amino acid sequence set forth in SEQ ID NO: 58, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 59, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 66, an LCDR2 amino acid sequence set forth in SEQ ID NO: 61, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 65; (g) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 74, an HCDR2 amino acid sequence set forth in SEQ ID NO: 75, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 76, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 77, an LCDR2 amino acid sequence set forth in SEQ ID NO: 78, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 73; (h) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 74, an HCDR2 amino acid sequence set forth in SEQ ID NO: 80, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 76, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 77, an LCDR2 amino acid sequence set forth in SEQ ID NO: 78, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 73; (i) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 88, an HCDR2 amino acid sequence set forth in SEQ ID NO: 89, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 90, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 91, an LCDR2 amino acid sequence set forth in SEQ ID NO: 92, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 87; (j) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 amino acid sequence set forth in SEQ ID NO: 101, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 102, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 103, an LCDR2 amino acid sequence set forth in SEQ ID NO: 61, and an LCDR3 amino -6- IPTS / 200096106.1Attorney Docket No. ITL-013WO acid sequence set forth in SEQ ID NO: 99; (k) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 amino acid sequence set forth in SEQ ID NO: 111, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 112, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 113, an LCDR2 amino acid sequence set forth in SEQ ID NO: 114, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 110; (l) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 amino acid sequence set forth in SEQ ID NO: 118, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 112, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 103, an LCDR2 amino acid sequence set forth in SEQ ID NO: 119, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 117; (m) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 amino acid sequence set forth in SEQ ID NO: 111, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 112, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 123, an LCDR2 amino acid sequence set forth in SEQ ID NO: 36, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 122; (n) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 amino acid sequence set forth in SEQ ID NO: 111, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 112, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 127, an LCDR2 amino acid sequence set forth in SEQ ID NO: 61, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 110; (o) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 amino acid sequence set forth in SEQ ID NO: 101, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 131, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 103, an LCDR2 amino acid sequence set forth in SEQ ID NO: 61, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 99; (p) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 amino acid sequence set forth in SEQ ID NO: 137, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 131, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 138, an LCDR2 amino acid sequence set forth in SEQ ID NO: 139, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 136; or (q) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 amino acid sequence set forth in SEQ ID NO: 111, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 131, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 127, an LCDR2 amino acid sequence set forth in SEQ ID NO: 61, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 142. -7- IPTS / 200096106.1Attorney Docket No. ITL-013WO

[0010] In some embodiments, the isolated antibody or antigen-binding fragment comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to an amino acid sequence as set forth in SEQ ID NO: 1, 13, 25, 37, 38, 51, 62, 67, 79, 81, 93, 104, 115, 124, 128, 132, or 140. In some embodiments, the isolated antibody or antigen-binding fragment comprises a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to an amino acid sequence as set forth in SEQ ID NO: 2, 14, 26, 39, 50, 52, 63, 68, 82, 94, 105, 116, 120, 125, 129, 133, 141, or 143. In some embodiments, the isolated antibody or antigen-binding fragment comprises (i) a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to an amino acid sequence as set forth in SEQ ID NO: 1, 13, 25, 37, 38, 51, 62, 67, 79, 81, 93, 104, 115, 124, 128, 132, or 140; and (ii) a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to an amino acid sequence as set forth in SEQ ID NO: 2, 14, 26, 39, 50, 52, 63, 68, 82, 94, 105, 116, 120, 125, 129, 133, 141, or 143.

[0011] In some embodiments, the isolated antibody or antigen-binding fragment is selected from the group consisting of an antibody, a single chain variable fragment (scFv), a Fab fragment, a Fab′ fragment, a single-chain Fab fragment (scFab), and a F(ab′)2fragment. In some embodiments, the antibody is an IgG1, an IgG2, an IgG3, an IgG4, an IgA, an IgD, an IgE, or an IgM antibody.

[0012] Also disclosed herein, in various embodiments, is an isolated antibody or antigen- binding fragment thereof that competes with the isolated antibody or antigen-binding fragment disclosed herein for binding to the P2X3 protein, the P2X2 protein, or the P2X2 / P2X3 heterodimer.

[0013] Also disclosed herein, in various embodiments, is an isolated antibody or antigen- binding fragment comprising a means for binding to a P2X3 protein, a P2X2 protein, or a P2X2 / P2X3 heterodimer. -8- IPTS / 200096106.1Attorney Docket No. ITL-013WO

[0014] Also disclosed herein, in various embodiments, is a pharmaceutical composition comprising the isolated antibody or antigen binding fragment disclosed herein. In some embodiments, the composition is an injectable pharmaceutical composition. In some embodiments, the composition is sterile. In some embodiments, the composition is pyrogen free. In some embodiments, the composition is free of antibodies that do not bind to P2X3.

[0015] Also disclosed herein, in various embodiments, is a method of treating, inhibiting or ameliorating a P2X3, a P2X2, or a P2X2 / P2X3 associated pathology comprising administering an isolated antibody or antigen binding fragment or a pharmaceutical composition disclosed herein. In some embodiments, the P2X3, P2X2, or a P2X2 / P2X3 associated pathology is pain. In some embodiments, the method alleviates the symptoms of a P2X3, a P2X2, or a P2X2 / P2X3 associated pain.

[0016] Also disclosed herein, in various embodiments, is a method of inhibiting a P2X3, a P2X2, or a P2X2 / P2X3 activity comprising contacting a P2X3, a P2X2, or a P2X2 / P2X3 protein with an isolated antibody or antigen binding fragment or a pharmaceutical composition disclosed herein. In some embodiments, the isolated antibody or antigen binding fragment is a human IgG antibody.

[0017] Also disclosed herein, in various embodiments, is a method of detecting the presence or absence of a P2X3 in a sample comprising contacting a sample with an isolated antibody or antigen binding fragment disclosed herein and detecting the binding to a P2X3 antigen by the isolated antibody or antigen binding fragment, wherein the detection of the binding indicates the presence of the P2X3 antigen; or the absence of the detection of the binding to the P2X3 antigen indicates the absence of the P2X3 antigen.

[0018] Also disclosed herein, in various embodiments, is a method of identifying an antibody that binds to an epitope on a P2X3 protein, a P2X2 protein, or a P2X2 / P2X3 heterodimer protein, the method comprising contacting a test antibody with the epitope on the P2X3 protein, the P2X2 protein, or the P2X2 / P2X3 heterodimer protein and determining whether the test antibody binds to the epitope, wherein the determining comprises determining whether an antibody disclosed herein competitively inhibits the binding of the test antibody to the epitope. In some embodiments, the determining comprises mutating one or more residues of epitope and determining binding of the test epitope, wherein if the mutation reduces binding of the test antibody, the test antibody is deemed to bind to that epitope. -9- IPTS / 200096106.1Attorney Docket No. ITL-013WO

[0019] Also disclosed herein, in various embodiments, is a method of inducing an immune response against a P2X3 antigen, a P2X2 antigen, or a P2X2 / P2X3 heterodimer antigen comprising administering the P2X3 antigen, the P2X2 antigen, or the P2X2 / P2X3 heterodimer antigen to a subject under conditions sufficient to induce an immune response. In some embodiments, the method comprises administering a lipoparticle comprising the P2X3 antigen, the P2X2 antigen, or the P2X2 / P2X3 heterodimer antigen to the subject. In some embodiments, the subject is a chicken. BRIEF DESCRIPTION OF DRAWINGS

[0020] These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, and accompanying drawings, where:

[0021] FIG.1 shows serum from a chicken immunized with P2X3 Lipoparticles that was tested by flow cytometry for reactivity against P2X3 (and a negative control receptor, CCR5) on heterologous cells.

[0022] FIG.2 shows a panel of 27 IgY antibody clones from P2X3 immunized chickens that were screened for reactivity to cell surface expressed P2X3. Each clone demonstrated robust reactivity to P2X3 (log scale, signal to noise ranging from 5 to 250 fold above background).

[0023] FIG.3 shows Left Panel: Lipoparticles containing P2X3, a GPCR (CXCR4), or no specific receptor (Null) were captured onto a Forte OctetRed biosensor, followed by kinetic measurements of a P2X3 monoclonal antibody (MAb clone 10). The inset shows a three point dose-response titration of the antibody against P2X3 Lipoparticles, used to approximate starting concentration points needed for a full kinetic series. Right Panel: P2X3 MAbs were tested by western blot against P2X3 Lipoparticles (+) or Null Lipoparticles lacking the ion channel (-). Two MAbs are shown (one linear, one conformational) along with the positive control (against the V5 epitope tag on P2X3, on the right). Arrow indicates band corresponding to P2X3.

[0024] FIG.4 shows Left Panel: HEK-293 cells were transfected with P2X3. The addition of α,β-meATP results in robust activation of P2X3, as seen by calcium flux. Pre-incubation of cells with 5 ug / ml P2X3 MAbs clone 19, 10, or 20 (variable chain fusions to human Fc) significantly reduced activation, demonstrating that these MAbs can inhibit P2X3 function. Right Panel: HEK-293 cells were transfected with P2X3 or a control receptor (T2R16) and -10- IPTS / 200096106.1Attorney Docket No. ITL-013WO activation in response to α,β-meATP (P2X3) or salicin (T2R16) was measured in duplicate (average + / - range shown). Pre-incubation of P2X3 with a control MAb or anti-P2X3 MAb B4 had no effect on P2X3 activation. P2X3 MAbs also had no effect on activation of the control receptor (T2R16). DETAILED DESCRIPTION:

[0025] The present disclosure provides antibodies or antigen-binding fragments thereof that bind to P2X3, P2X2, and / or a P2X2 / P2X3 heterodimer. Definitions

[0026] Terms used in the claims and specification are defined as set forth below unless otherwise specified.

[0027] It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise.

[0028] The term “antibody” as used herein is meant in a broad sense and includes immunoglobulin or antibody molecules including polyclonal antibodies, monoclonal antibodies including murine, human, humanized and chimeric monoclonal antibodies and antibody fragments. The antibodies described herein can include, but are not limited to, at least one of a heavy chain constant region (Hc), a heavy chain variable region (Hv), a light chain variable region (Lv) and a light chain constant region (Lc), wherein a polyclonal Ab, monoclonal Ab, fragment and / or regions thereof include at least one heavy chain variable region (Hv) or light chain variable region (Lv) which binds a portion of a P2X3 and can be used to detect the antigen. The antibodies can also be monoclonal antibodies that are made by immunizing chickens. The variable chains from the nucleic acid sequences encoding the isolated monoclonal antibodies can be isolated by using techniques, such as but not limited to, PCR. The variable chains isolated by these techniques can then be placed in a scFv vector with a human Fc. Accordingly, the antibodies can be antibodies that have a human Fc and two scFv arms. The antibodies, such as those described here and throughout the present disclosure can then be modified to be human or humanized antibodies. Examples of how to modify an antibody, including chicken antibodies, can be found in, for example, Riechmann L, Clark M, Waldmann H, Winter G (1988). Reshaping human antibodies for therapy". Nature 332 (6162): 332–323; Tsurushita N, Park M, Pakabunto K, Ong K, Avdalovic A, Fu H, Jia A, Vásquez M, Kumar S. (2004); and “Humanization of a chicken anti-IL-12 -11- IPTS / 200096106.1Attorney Docket No. ITL-013WO monoclonal antibody” Immunol Methods 295 (1-2): 9-19; Nishibori N, Horiuchi H, Furusawa S, Matsuda H. (2006) “Humanization of chicken monoclonal antibody using phage display system” Mol Immunol.43 (6): 634-42, each of which is incorporated by reference in its entirety.

[0029] In general, antibodies are proteins or polypeptides that exhibit binding specificity to a specific antigen. Intact antibodies are heterotetrameric glycoproteins, composed of two identical light chains and two identical heavy chains. Typically, each light chain is linked to a heavy chain by one covalent disulfide bond, while the number of disulfide linkages varies between the heavy chains of different immunoglobulin isotypes. Each heavy and light chain also has regularly spaced intrachain disulfide bridges. Each heavy chain has at one end a variable domain (VH) followed by a number of constant domains. Each light chain has a variable domain at one end (VL) and a constant domain at its other end; the constant domain of the light chain is aligned with the first constant domain of the heavy chain and the light chain variable domain is aligned with the variable domain of the heavy chain. The VH and VL domains consist of four regions of relatively conserved sequences named framework regions (FR1, FR2, FR3, and FR4), which form a scaffold for three regions of hypervariable sequences (complementarity determining regions, CDRs).

[0030] Antibody light chains of any vertebrate species can be assigned to one of two clearly distinct types, namely kappa (κ) and lambda (λ), based on the amino acid sequences of their constant domains. Immunoglobulins can be assigned to five major classes, namely IgA, IgD, IgE, IgG and IgM, depending on the heavy chain constant domain amino acid sequence. IgA and IgG are further sub-classified as the isotypes IgA1, IgA2, IgG1, IgG2, IgG3 and IgG4. The subunit structures and three-dimensional configurations of different classes of immunoglobulins are well known in the art. For a review of the antibody structure, see Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory, Eds. Harlow et al., 1988. One of skill in the art will recognize that each subunit structure, e.g., a CH, VH, CL, VL, CDR, and / or FR structure, comprises active fragments. For example, active fragments may consist of the portion of the VH, VL, or CDR subunit that binds the antigen, i.e., the antigen- binding fragment, or the portion of the CH subunit that binds to and / or activates an Fc receptor and / or complement.

[0031] The term “humanized antibody”, “engineered antibody”, "human framework adapted", and "HFA" as used herein, is intended to include antibodies having variable region frameworks derived from sequences of human origin. Furthermore, if the antibody contains a -12- IPTS / 200096106.1Attorney Docket No. ITL-013WO constant region, the constant region can be derived from such human sequences, e.g., human germline sequences, or naturally occurring (e.g., allotypes) or mutated versions of human germline sequences. The humanized antibodies may include amino acid residues not encoded by human sequences (e.g., mutations introduced by random or site-specific mutagenesis in vitro or by somatic mutation in vivo).

[0032] The term “antibody fragment” means a portion of an intact antibody, generally the antigen binding or variable region of the intact antibody. Examples of antibody fragments include Fab, Fab', F(ab')2 and Fv fragments, diabodies, single chain antibody molecules and multispecific antibodies formed from at least two intact antibodies.

[0033] The term “antigen” as used herein means any molecule that has the ability to generate antibodies either directly or indirectly. Included within the definition of “antigen” is a protein-encoding nucleic acid. An antigen can have one or more than one epitope. The specific reaction referred to above is meant to indicate that the antigen will react, in a highly selective manner, with its corresponding antibody and not with the multitude of other antibodies which can be evoked by other antigens. In some embodiments, antigens that bind antibodies, fragments and regions of the antibodies include at least 5 amino acids. In some embodiments, the antigen is the P2X3 protein expressed on the surface of a cell or particle. In some embodiments, the cell is an intact cell. An intact cell is a cell that has not been lysed or broken open with the use of detergents or other reagents. A cell that has been treated with detergents or other reagents that breaks up the cellular membrane or punches holes in a cellular membrane is not an intact cell. By expressing the receptor on the surface of the cell or particle, e.g., lipoparticle, the receptor can present conformational epitopes that may otherwise not be present if purified protein is used. An example is provided herein. In some embodiments, an adjuvant is not used, but an adjuvant can be used. In some embodiments, the particles are injected into a bird (e.g., chicken) to stimulate an immune response and generate antibodies against the protein present on the surface of the particle. Particles suitable for the generation of antibodies are described in U.S. Patent Nos.: 8,377,691, 7,763,258, 8,158,130 and U.S. Patent Application Publication Nos.20050123563 and 20120195882, each of which is hereby incorporated by reference. These publications and patents describe the generation of various particles, including lipoparticles, that can be used to express membrane spanning proteins (e.g., multiple-membrane spanning proteins, ion channels, and the like). -13- IPTS / 200096106.1Attorney Docket No. ITL-013WO

[0034] As used herein, “bind” refers to antibody binding to a predetermined antigen (e.g., P2X2, P2X3, P2X2 / P2X3 heterodimer) or epitope present on the antigen. With regard to the binding of an antibody to a target molecule, the terms “specific binding,” “specifically binds to,” “specific for,” “selectively binds,” “selective for,” “immunospecific binding,” or “binds immunospecifically” to a particular antigen (e.g., a polypeptide target) or an epitope on a particular antigen mean binding that is measurably different from a non-specific or non- selective interaction (e.g., with a non-target molecule). For example, an antibody that “selectively binds” or “specifically binds” an antigen is an antigen-binding moiety that binds the antigen with high affinity and does not significantly bind other unrelated antigens. Specific binding can be measured, for example, by measuring binding to a target molecule and comparing it to binding to a non-target molecule. Specific binding can also be determined by competition with a control molecule that mimics the epitope recognized on the target molecule. In that case, specific binding is indicated if the binding of the antibody to the target molecule is competitively inhibited by the control molecule. Specific binding is characterized by a high affinity and is selective for the compound, protein, epitope, or antigen. Nonspecific binding usually has a low affinity. Binding in IgG antibodies for example is generally characterized by an affinity of at least about 10-7M or higher, such as at least about 10-8M or higher, or at least about 10-9M or higher, or at least about 10-10or higher, or at least about 10-11M or higher, or at least about 10-12M or higher. The term is also applicable where, e.g., an antigen-binding domain is specific for a particular epitope that is not carried by numerous antigens, in which case the antibody or antigen binding protein carrying the antigen-binding domain will generally not bind other antigens. In some embodiments, the capture reagent has a Kd equal or less than 10-9M, 10-10M, or 10-11M for its binding partner (e.g., antigen). In some embodiments, the capture reagent has a Ka greater than or equal to 109M-1for its binding partner.

[0035] The term “complementarity determining region” “CDR,” as used herein, refers to each of the regions of an antibody variable domain which are hypervariable in sequence and / or form structurally defined loops (“hypervariable loops,” “hypervariable region,” or “HVR”). Generally, native four-chain antibodies comprise six CDRs; three in the VH (HCDR1, HCDR2, and HCDR3), and three in the VL (LCDR1, LCDR2, and LCDR3). With the exception of CDR1 in VH, CDRs generally comprise the amino acid residues that form the hypervariable loops. Complementarity determining regions (CDRs) are also referred to as “hypervariable regions” or “HVRs”, and these terms are used herein interchangeably in -14- IPTS / 200096106.1Attorney Docket No. ITL-013WO reference to portions of the variable region that form the antigen-binding regions. This particular region has been described by Kabat et al., U.S. Dept. of Health and Human Services, Sequences of Proteins of Immunological Interest (1983) and by Chothia et al., J Mol Biol 196:901-917 (1987), where the definitions include overlapping or subsets of amino acid residues when compared against each other. There are six HVRs, three in VH (H1, H2, H3) and three in VL (L1, L2, L3). Chothia and Lesk refer to structurally conserved HVs as "canonical structures." Another method of describing the regions that form the antigen- binding site has been proposed by Lefranc (Lefranc et al., Developmental & Comparative Immunology 27:55-77, 2003) based on the comparison of V domains from immunoglobulins and T-cell receptors (Lefranc et al., Developmental & Comparative Immunology 27:55-77, 2003). The antigen-binding site can also be delineated based on "Specificity Determining Residue Usage (SDRU)", according to Almagro (Almagro, Mol. Recognit.17:132-43, 2004), where SDRU refers to amino acid residues of an immunoglobulin that are directly involved in antigen contact. Nevertheless, application of either definition to refer to a CDR of an antibody or variants thereof is intended to be within the scope of the term as defined and used herein. The exact residue numbers which encompass a particular CDR will vary depending on the sequence and size of the CDR. Those skilled in the art can routinely determine which residues comprise a particular CDR given the variable region amino acid sequence of the antibody.

[0036] CDRs provide the majority of contact residues for the binding of the antibody to the antigen or epitope. CDRs of interest can be derived from donor antibody variable heavy and light chain sequences, and include analogs of the naturally occurring CDRs, which analogs also share or retain the same antigen binding specificity and / or neutralizing ability as the donor antibody from which they were derived.

[0037] The amino acid sequence boundaries of a CDR can be determined by one of skill in the art using any of a number of known numbering schemes, including those described by Kabat et al., supra (“Kabat” numbering scheme); Al-Lazikani et al., 1997, J. Mol. Biol., 273:927-948 (“Chothia” numbering scheme); Martin (“Enhanced Chothia” or “AbM”) Abhinandan and Martin, Mol Immunol.2008 Aug;45(14):3832-9; MacCallum et al., 1996, J. Mol. Biol.262:732-745 (“Contact” numbering scheme); Lefranc et al., Dev. Comp. Immunol., 2003, 27:55-77 (“IMGT” numbering scheme); and Honegger and Plückthun, J. Mol. Biol., 2001, 309:657-70 (“AHo” numbering scheme); each of which is incorporated by reference in its entirety. -15- IPTS / 200096106.1Attorney Docket No. ITL-013WO

[0038] CDRs may be assigned, for example, using antibody numbering software, such as Abnum, available at bioinf.org.uk / abs / abnum / , and described in Abhinandan and Martin, Immunology, 2008, 45:3832-3839, incorporated by reference in its entirety. Descriptions of the various antibody numbering schemes are available at bioinf.org.uk / abs / info.html and the AbYsis program.

[0039] Table 1 provides the positions of LCDR1, LCDR2, LCDR3, HCDR1, HCDR2, and HCDR-H3 as identified by the Kabat, Chothia, AbM, Contact, and IMGT schemes. For HCDR1, residue numbering is provided using both the Kabat and Chothia numbering schemes. Table 1: Residues in CDRs according to Kabat and Chothia numbering schemes. CDR Kabat Chothia AbM Contact IMGT L1 L24-L34 L24-L34 L24-L34 L30-L36 L27-L32

[0040] The “EU numbering scheme” is generally used when referring to a residue in an antibody heavy chain constant region (e.g., as reported in Kabat et al., supra). Unless stated otherwise, the EU numbering scheme is used to refer to residues in antibody heavy chain constant regions described herein.

[0041] The term “homolog” means protein sequences having between 40% and 100% sequence identity to a reference sequence. Percent identity between two peptide chains can be determined by pair wise alignment using the default settings of the AlignX module of Vector NTI v.9.0.0 (Invitrogen Corp., Carslbad, Calif.). In some embodiments, the an antibody or fragment thereof has at least 50, 60, 70, 80, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99% identity to a sequence described herein. In some embodiments, the antibody has conservative substitutions as compared to a sequence described herein. Antibodies having conservative substitutions in the heavy and light chain sequences shown in Table 1 are encompassed within the scope of the disclosed subject matter. The conservative substitution may reside in the framework regions, or in antigen-binding sites, as long they do not -16- IPTS / 200096106.1Attorney Docket No. ITL-013WO adversely affect the properties of the antibody. Substitutions may be made to improve antibody properties, for example stability or affinity. Conservative substitutions will produce molecules having functional and chemical characteristics similar to those molecules into which such modifications are made. Exemplary amino acid substitutions are shown in the table below. Table 2: Example Conservative Substitutions Original Residue Exemplary Conservative Substitutions Ala Val, Leu, Ile

[0042] Thbed agents can be administered to an animal together in a mixture, concurrently as single agents or sequentially as single agents in any order.

[0043] Polyclonal antibodies are heterogeneous populations of antibody molecules derived from the sera of animals immunized with an antigen. A monoclonal antibody (MAb) contains a substantially homogeneous population of antibodies specific to antigens, which population contains substantially similar epitope binding sites. MAbs may be obtained by methods known to those skilled in the art. See, for example Kohler and Milstein, Nature 256:495497 (1975); U.S. Pat. No.4,376,110; Ausubel et al., eds., Current Protocols in Molecular Biology, Greene Publishing Assoc. and Wiley Interscience, N.Y., (1987, 1992); and Harlow and Lane ANTIBODIES: A Laboratory Manual Cold Spring Harbor Laboratory (1988); Colligan et al., eds., Current Protocols in Immunology, Greene Publishing Assoc. and Wiley Interscience, -17- IPTS / 200096106.1Attorney Docket No. ITL-013WO N.Y., (1992, 1993), the contents of which references are incorporated entirely herein by reference. Such antibodies may be of any immunoglobulin class including IgG, IgM, IgE, IgA, GILD and any subclass thereof. A hybridoma producing a mAb may be cultivated in vitro, in situ or in vivo. Production of high titers of mAbs in vivo or in situ makes this the presently preferred method of production.

[0044] Chimeric antibodies are molecules different portions of which are derived from different animal species, such as those having variable region derived from a murine mAb and a human immunoglobulin constant region, which are primarily used to reduce immunogenicity in application and to increase yields in production, for example, where murine mAbs have higher yields from hybridomas but higher immunogenicity in humans, such that human / murine chimeric mAbs are used. Chimeric antibodies and methods for their production are known in the art (Cabilly et al., Proc. Natl. Acad. Sci. USA 81:32733277 (1984); Morrison et al., Proc. Natl. Acad. Sci. USA 81:68516855 (1984); Boulianne et al., Nature 312:643646 (1984); Cabilly et al., European Patent Application 125023 (published Nov.14, 1984); Neuberger et al., Nature 314:268270 (1985); Taniguchi et al., European Patent Application 171496 (published Feb.19, 1985); Morrison et al., European Patent Application 173494 (published Mar.5, 1986); Neuberger et al., PCT Application WO 86 / 01533, (published Mar.13, 1986); Kudo et al., European Patent Application 184187 (published Jun.11, 1986); Morrison et al., European Patent Application 173494 (published Mar.5, 1986); Sahagan et al., J. Immunol.137:10661074 (1986); Robinson et al., International Patent Publication #PCT / US86 / 02269 (published May 7, 1987); Liu et al., Proc. Natl. Acad. Sci. USA 84:34393443 (1987); Sun et al., Proc. Natl. Acad. Sci. USA 84:214 218 (1987); Better et al., Science 240:10411043 (1988); and Harlow and Lane Antibodies. a Laboratory Manual Cold Spring Harbor Laboratory (1988)). These references are entirely incorporated herein by reference.

[0045] An anti-idiotypic (anti-Id) antibody is an antibody which recognizes unique determinants generally associated with the antigen-binding site of an antibody. An Id antibody can be prepared by immunizing an animal of the same species and genetic type (e.g., mouse strain) as the source of the mAb with the mAb to which an anti-Id is being prepared. The immunized animal will recognize and respond to the idiotypic determinants of the immunizing antibody by producing an antibody to these idiotypic determinants (the anti- Id antibody). See, for example, U.S. Pat. No.4,699,880, which is herein entirely incorporated by reference. The anti-Id antibody may also be used as an “immunogen” to induce an -18- IPTS / 200096106.1Attorney Docket No. ITL-013WO immune response in yet another animal, producing a so-called anti-anti-Id antibody. The anti- anti-Id may be epitopically identical to the original mAb which induced the anti-Id. Thus, by using antibodies to the idiotypic determinants of a mAb, it is possible to identify other clones expressing antibodies of identical specificity.

[0046] The term “monoclonal antibody” (mAb) as used herein means an antibody (or antibody fragment) obtained from a population of substantially homogeneous antibodies. Monoclonal antibodies are highly specific, typically being directed against a single antigenic determinant. The modifier “monoclonal” indicates the substantially homogeneous character of the antibody and does not require production of the antibody by any particular method. For example, murine mAbs can be made by the hybridoma method of Kohler et al., Nature 256:495-497 (1975). Chimeric mAbs containing a light chain and heavy chain variable region derived from a donor antibody (typically murine) in association with light and heavy chain constant regions derived from an acceptor antibody (typically another mammalian species such as human) can be prepared by the method disclosed in U.S. Pat. No.4,816,567. Humanized mAbs having CDRs derived from a non-human donor immunoglobulin (typically murine) and the remaining immunoglobulin-derived parts of the molecule being derived from one or more human immunoglobulins, optionally having altered framework support residues to preserve binding affinity, can be obtained by the techniques disclosed in Queen et al., Proc. Natl. Acad. Sci. (USA), 86:10029-10032 (1989) and Hodgson et al., Bio / Technology, 9:421 (1991).

[0047] In addition to the antibodies described herein, exemplary human framework sequences useful for humanization are disclosed at, e.g., www.ncbi.nlm.nih.gov / entrez / query.fcgi; www.ncbi.nih.gov / igblast; www.atcc.org / phage / hdb.html; www.mrc-cpe.cam.ac.uk / ALIGNMENTS.php; www.kabatdatabase.com / top.html; ftp.ncbi.nih.gov / repository / kabat; www.sciquest.com; www.abcam.com; www.antibodyresource.com / onlinecomp.html; www.public.iastate.edu / .about.pedro / research_tools.html; www.whfreeman.com / immunology / CH05 / kuby05.htm; www.hhmi.org / grants / lectures / 1996 / vlab; www.path.cam.ac.uk / .about.mrc7 / mikeimages.html; mcb.harvard.edu / BioLinks / Immunology.html; www.immunologylink.com; pathbox.wustl.edu / .about.hcenter / index.html; www.appliedbiosystems.com; www.nal.usda.gov / awic / pubs / antibody; www.m.ehime-u.ac.jp / .about.yasuhito / Elisa.html; -19- IPTS / 200096106.1Attorney Docket No. ITL-013WO www.biodesign.com; www.cancerresearchuk.org; www.biotech.ufl.edu; www.isac-net.org; baserv.uci.kun.nl / .about.jraats / links1.html; www.recab.uni-hd.de / immuno.bme.nwu.edu; www.mrc-cpe.cam.ac.uk; www.ibt.unam.mx / vir / V_mice.html; http: / / www.bioinf.org.uk / abs; antibody.bath.ac.uk; www.unizh.ch; www.cryst.bbk.ac.uk / .about.ubcg07s; www.nimr.mrc.ac.uk / CC / ccaewg / ccaewg.html; www.path.cam.ac.uk / .about.mrc7 / humanisation / TAHHP.html; www.ibt.unam.mx / vir / structure / stat_aim.html; www.biosci.missouri.edu / smithgp / index.html; www.jerini.de; imgt.cines.fr; and Kabat et al., Sequences of Proteins of Immunological Interest, U.S. Dept. Health (1987), each entirely incorporated herein by reference.

[0048] Methods for determining mAb specificity and affinity by competitive inhibition can be found in Harlow, et al., Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1988), Colligan et al., eds., Current Protocols in Immunology, Greene Publishing Assoc. and Wiley Interscience, N.Y., (1992, 1993), and Muller, Meth. Enzymol.92:589601 (1983), which references are entirely incorporated herein by reference.

[0049] The techniques to raise antibodies to small peptide sequences that recognize and bind to those sequences in the free or conjugated form or when presented as a native sequence in the context of a large protein are well known in the art. Such antibodies include murine, murine-human and human-human antibodies produced by hybridoma or recombinant techniques known in the art. Antibodies can also be produced in chickens, goats, rabbits, or other small animals.

[0050] As used herein, the term “antigen binding region” refers to that portion of an antibody molecule which contains the amino acid residues that interact with an antigen (e.g., P2X3, P2X2, or a P2X2 / P2X3 heterodimer) and confer on the antibody its specificity and affinity for the antigen. The antibody region includes the “framework” amino acid residues necessary to maintain the proper conformation of the antigen-binding residues. In some embodiments, the antigen binding region will be of murine origin. In some embodiments, the antigen binding region can be derived from other animal species, in particular rodents such as rabbit, rat or hamster, or birds such as chickens. It has been shown that the antigen-binding function of an antibody can be performed by fragments of a full-length antibody. Examples of binding fragments encompassed within the term “antigen-binding portion” or “antigen- binding fragment” of an antibody include a Fab fragment, a monovalent fragment having the VL, VH, CL and CH1 domains; a F(ab)2 fragment, a bivalent fragment comprising two Fab -20- IPTS / 200096106.1Attorney Docket No. ITL-013WO fragments linked by a disulfide bridge(s) at a hinge region; a Fd fragment having the VH and CH1 domains; a Fv fragment having the VL and VH domains of a single arm of an antibody; a domain antibody or dAb fragment (Ward et al., 1989 Nature 341:544-546), which consists of a VH domain; and an isolated complementarity determining region (CDR), especially a CDR3 (See for example the WO03 / 025019, the contents of which are incorporated herein by reference).

[0051] Furthermore, although the two domains of the Fv fragment, VL and VH, are encoded by separate genes naturally, they can be joined, using recombinant methods, by a synthetic linker that enables them to be made as a single protein chain in which the VL and VH regions pair to form monovalent molecules (known as single chain Fv (scFv); see e.g., Bird et al., 1988 Science 242:423-426; and Huston et al., 1988 Proc. Nat. Acad. Sci. 85:5879-5883). Such single chain antibodies are encompassed by the term "antigen-binding portion" of an antibody. These antibody fragments are obtained using conventional techniques known to those of skill in the art, and can be used in the same manner as intact antibodies.

[0052] The variable regions described herein can be combined with any type of constant region including a human constant region or murine constant region. Human genes which encode the constant (C) regions of the antibodies, fragments and regions can be derived from a human fetal liver library, by known methods. Human C regions genes can be derived from any human cell including those which express and produce human immunoglobulins. The human CHregion can be derived from any of the known classes or isotypes of human H chains, including gamma, µ, α, δ or ε, and subtypes thereof, such as G1, G2, G3 and G4. Since the H chain isotype is responsible for the various effector functions of an antibody, the choice of CH region will be guided by the desired effector functions, such as complement fixation, or activity in antibody-dependent cellular cytotoxicity (ADCC). Preferably, the CH region is derived from gamma 1 (IgG1), gamma 3 (IgG3), gamma 4 (IgG4), or µ (IgM). The human CL region can be derived from either human L chain isotype, kappa or lambda.

[0053] One common feature of all immunoglobulin H and L chain genes and their encoded mRNAs is the J region. H and L chain J regions have different sequences, but a high degree of sequence homology exists (greater than 80%) among each group, especially near the C region. This homology is exploited in this method and consensus sequences of H and L chain J regions can be used to design oligonucleotides for use as primers for introducing useful -21- IPTS / 200096106.1Attorney Docket No. ITL-013WO restriction sites into the J region for subsequent linkage of V region segments to human C region segments.

[0054] C region cDNA vectors prepared from human cells can be modified by site-directed mutagenesis to place a restriction site at the analogous position in the human sequence. For example, one can clone the complete human kappa chain C (Ck) region and the complete human gamma-1 C region (Cγ-1). In this case, the alternative method based upon genomic C region clones as the source for C region vectors would not allow these genes to be expressed in bacterial systems where enzymes needed to remove intervening sequences are absent. Cloned V region segments are excised and ligated to L or H chain C region vectors. Alternatively, the human Cγ-1 region can be modified by introducing a termination codon thereby generating a gene sequence which encodes the H chain portion of an Fab molecule. The coding sequences with linked V and C regions are then transferred into appropriate expression vehicles for expression in appropriate hosts, prokaryotic or eukaryotic.

[0055] An “isolated antibody,” as used herein, refers to an antibody that is substantially free of other antibodies having different antigenic specificities (e.g., an isolated antibody that specifically binds P2X3 is substantially free of antibodies that specifically bind antigens other than P2X3). In some embodiments, the antibody may cross react with P2X2 or the heterodimer P2X2 / P2X3. Moreover, an isolated antibody may be substantially free of other cellular material and / or chemicals. An isolated antibody can also be sterile or pyrogen free or formulated as injectable pharmaceutical as described herein.

[0056] In some embodiments, the source for the DNA encoding a non-human antibody include cell lines which produce antibody, such as hybrid cell lines commonly known as hybridomas.

[0057] The term “epitope” is meant to refer to that portion of any molecule capable of being recognized by and bound by an antibody at one or more of the Ab’s antigen binding regions. Epitopes usually consist of chemically active surface groupings of molecules such as amino acids or sugar side chains and have specific three dimensional structural characteristics as well as specific charge characteristics. Example of epitopes include, but are not limited to,

[0058] As used herein, the term “chimeric antibody” includes monovalent, divalent or polyvalent immunoglobulins. A monovalent chimeric antibody is a dimer (HL) formed by a chimeric H chain associated through disulfide bridges with a chimeric L chain. A divalent chimeric antibody is tetramer (H2L2) formed by two HL dimers associated through at least -22- IPTS / 200096106.1Attorney Docket No. ITL-013WO one disulfide bridge. A polyvalent chimeric antibody can also be produced, for example, by employing a CHregion that aggregates (e.g., from an IgM H chain, or µ chain).

[0059] A chimeric antibody, such as a mouse-human or human-human, can be synthesized from genes driven by the chromosomal gene promoters native to the mouse H and L chain V regions used in the constructs; splicing usually occurs between the splice donor site in the mouse J region and the splice acceptor site preceding the human C region and also at the splice regions that occur within the human C region; polyadenylation and transcription termination occur at native chromosomal sites downstream of the human coding regions.

[0060] Antibodies, fragments or derivatives having chimeric H chains and L chains of the same or different variable region binding specificity, can also be prepared by appropriate association of the individual polypeptide chains, according to known method steps, e.g., according to Ausubel infra, Harlow infra, and Colligan infra, the contents of which references are incorporated entirely herein by reference. With this approach, hosts expressing chimeric H chains (or their derivatives) are separately cultured from hosts expressing chimeric L chains (or their derivatives), and the immunoglobulin chains are separately recovered and then associated. Alternatively, the hosts can be co-cultured and the chains allowed to associate spontaneously in the culture medium, followed by recovery of the assembled immunoglobulin, fragment or derivative.

[0061] The hybrid cells are formed by the fusion of a non-human antibody-producing cell, typically a spleen cell of an animal immunized against either natural or recombinant antigen, or a peptide fragment of the antigen protein sequence. Alternatively, the non-human antibody-producing cell can be a B lymphocyte obtained from the blood, spleen, lymph nodes or other tissue of an animal immunized with the antigen.

[0062] The second fusion partner, which provides the immortalizing function, can be a lymphoblastoid cell or a plasmacytoma or myeloma cell, which is not itself an antibody producing cell, but is malignant. Fusion partner cells include, but are not limited to, the hybridoma SP2 / 0-Ag14, abbreviated as SP2 / 0 (ATCC CRL1581) and the myeloma P3X63Ag8 (ATCC TIB9), or its derivatives. See, e.g., Ausubel infra, Harlow infra, and Colligan infra, the contents of which references are incorporated entirely herein by reference.

[0063] These antibodies can be obtained using conventional techniques known to those skilled in the art and described herein, and the fragments are used in the same manner as intact antibodies. Antibody diversity is created by multiple germline genes encoding variable -23- IPTS / 200096106.1Attorney Docket No. ITL-013WO domains and a variety of somatic events. The somatic events include recombination of variable gene segments with diversity (D) and joining (J) gene segments to make a complete VH domain, and the recombination of variable and joining gene segments to make a complete VL domain. The recombination process itself is imprecise, resulting in the loss or addition of amino acids at the V(D)J junctions. These mechanisms of diversity occur in the developing B cell prior to antigen exposure. After antigenic stimulation, the expressed antibody genes in B cells undergo somatic mutation. Based on the estimated number of germline gene segments, the random recombination of these segments, and random VH-VL pairing, up to 1.6X107different antibodies may be produced (Fundamental Immunology, 3rd ed. (1993), ed. Paul, Raven Press, New York, N.Y.). When other processes that contribute to antibody diversity (such as somatic mutation) are taken into account, it is thought that upwards of 1X1010different antibodies may be generated (Immunoglobulin Genes, 2nd ed. (1995), eds. Jonio et al., Academic Press, San Diego, Calif.). Because of the many processes involved in generating antibody diversity, it is unlikely that independently derived monoclonal antibodies with the same antigen specificity will have identical amino acid sequences.

[0064] Antibody or antigen binding protein molecules capable of specifically interacting with the antigens, epitopes, or other molecules described herein may be produced by methods well known to those skilled in the art. For example, monoclonal antibodies can be produced by generation of hybridomas in accordance with known methods. Hybridomas formed in this manner can then be screened using standard methods, such as enzyme-linked immunosorbent assay (ELISA) and biosensor analysis, to identify one or more hybridomas that produce an antibody that specifically interacts with a molecule or compound of interest.

[0065] As an alternative to preparing monoclonal antibody-secreting hybridomas, a monoclonal antibody to a polypeptide may be identified and isolated by screening a recombinant combinatorial immunoglobulin library (e.g., an antibody phage display library) with a polypeptide described herein to thereby isolate immunoglobulin library members that bind to the polypeptide. Techniques and commercially available kits for generating and screening phage display libraries are well known to those skilled in the art. Additionally, examples of methods and reagents particularly amenable for use in generating and screening antibody or antigen binding protein display libraries can be found in the literature. Thus, the epitopes described herein can be used to screen for other antibodies that can be used therapeutically, diagnostically, or as research tools. The antibodies can be generated -24- IPTS / 200096106.1Attorney Docket No. ITL-013WO according the examples provided herein. Once the sequences are known, the antibodies can also be generated according to known methods. The antibodies can also be converted to different types, such as being converted to Human IgGs and the like. By converting the antibodies to a human antibody, a human subject should not identify the antibodies as foreign. This will lead to a more effective response. The conversion of a non-human IgG antibody to a human IgG antibody is well known and can routinely be done once the native sequence is known. As discussed herein, the antibodies can be modified according to known methods. Such methods are described in, for example, Riechmann L, Clark M, Waldmann H, Winter G (1988). “Reshaping human antibodies for therapy”. Nature 332 (6162): 332–323; Tsurushita N, Park M, Pakabunto K, Ong K, Avdalovic A, Fu H, Jia A, Vásquez M, Kumar S. (2004); and “Humanization of a chicken anti-IL-12 monoclonal antibody” Immunol Methods 295 (1-2): 9-19; Nishibori N, Horiuchi H, Furusawa S, Matsuda H. (2006) “Humanization of chicken monoclonal antibody using phage display system” Mol Immunol. 43 (6): 634-42, each of which is incorporated by reference in its entirety.

[0066] The antibody-producing cell contributing the nucleotide sequences encoding the antigen-binding region of the chimeric antibody can also be produced by transformation of a non-human, such as a primate, or a human cell. For example, a B lymphocyte which produces the antibody can be infected and transformed with a virus such as Epstein-Barr virus to yield an immortal antibody producing cell (Kozbor et al., Immunol. Today 4:7279 (1983)). Alternatively, the B lymphocyte can be transformed by providing a transforming gene or transforming gene product, as is well-known in the art. See, e.g, Ausubel infra, Harlow infra, and Colligan infra, the contents of which references are incorporated entirely herein by reference.

[0067] The cell fusions are accomplished by standard procedures well known to those skilled in the field of immunology. Fusion partner cell lines and methods for fusing and selecting hybridomas and screening for mAbs are well known in the art. See, e.g., Ausubel infra, Harlow infra, and Colligan infra, the contents of which references are incorporated entirely herein by reference.

[0068] The antigen-specific murine or chimeric mAb can be produced in large quantities by injecting hybridoma or transfectoma cells secreting the antibody into the peritoneal cavity of mice and, after appropriate time, harvesting the ascites fluid which contains a high titer of the mAb, and isolating the mAb therefrom. For such in vivo production of the mAb with a non- murine hybridoma (e.g., rat or human), hybridoma cells are preferably grown in irradiated or -25- IPTS / 200096106.1Attorney Docket No. ITL-013WO athymic nude mice. Alternatively, the antibodies can be produced by culturing hybridoma or transfectoma cells in vitro and isolating secreted mAb from the cell culture medium or recombinantly, in eukaryotic or prokaryotic cells.

[0069] “Affinity” refers to the strength of the sum total of non-covalent interactions between a single binding site of a molecule (e.g., an antibody) and its binding partner (e.g., an antigen or epitope). Unless indicated otherwise, as used herein, “affinity” refers to intrinsic binding affinity, which reflects a 1:1 interaction between members of a binding pair (e.g., antibody and antigen or epitope). The affinity of a molecule X for its partner Y can be represented by the dissociation equilibrium constant (KD). The kinetic components that contribute to the dissociation equilibrium constant are described in more detail below. Affinity can be measured by common methods known in the art, including, but not limited to, surface plasmon resonance (SPR) technology (e.g., BIACORE®) or biolayer interferometry (e.g., FORTEBIO®).

[0070] In some embodiments, “derivatives” of the antibodies, fragments, regions or derivatives thereof, which term includes those proteins encoded by truncated or modified genes to yield molecular species functionally resembling the immunoglobulin fragments are provided. The modifications include, but are not limited to, addition of genetic sequences coding for cytotoxic proteins such as plant and bacterial toxins. The modification can also included a reporter protein, such as a fluorescent or chemiluminescent tag. The fragments and derivatives can be produced in any manner.

[0071] Fragments include, for example, Fab, Fab', F(ab')2and Fv. These fragments lack the Fc fragment of intact antibody, clear more rapidly from the circulation, and can have less non-specific tissue binding than an intact antibody (Wahl et al., J. Nucl. Med.24:316325 (1983)). These fragments are produced from intact antibodies using methods well known in the art, for example by proteolytic cleavage with enzymes such as papain (to produce Fab fragments) or pepsin (to produce F(ab')2fragments).

[0072] The identification of these antigen binding regions and / or epitopes recognized by antibodies described herein provide the information necessary to generate additional monoclonal antibodies with similar binding characteristics and therapeutic or diagnostic utility that parallel the embodiments of this application.

[0073] As used herein, the term “single-chain” refers to a molecule comprising amino acid monomers linearly linked by peptide bonds. In a particular such embodiment, the C-terminus -26- IPTS / 200096106.1Attorney Docket No. ITL-013WO of the Fab light chain is connected to the N-terminus of the Fab heavy chain in the single- chain Fab molecule. As described in more detail herein, an scFv has a variable domain of light chain (VL) connected from its C-terminus to the N-terminal end of a variable domain of heavy chain (VH) by a polypeptide chain. Alternately the scFv comprises of polypeptide chain where in the C-terminal end of the VH is connected to the N-terminal end of VL by a polypeptide chain.

[0074] The “Fab fragment” (also referred to as fragment antigen-binding) contains the constant domain (CL) of the light chain and the first constant domain (CH1) of the heavy chain along with the variable domains VL and VH on the light and heavy chains respectively. The variable domains comprise the complementarity determining loops (CDR, also referred to as hypervariable region) that are involved in antigen-binding. Fab′ fragments differ from Fab fragments by the addition of a few residues at the carboxy terminus of the heavy chain CH1 domain including one or more cysteines from the antibody hinge region.

[0075] “F(ab')2” fragments contain two Fab′ fragments joined, near the hinge region, by disulfide bonds. F(ab')2 fragments may be generated, for example, by recombinant methods or by pepsin digestion of an intact antibody. The F(ab') fragments can be dissociated, for example, by treatment with β-mercaptoethanol.

[0076] “Fv” fragments comprise a non-covalently-linked dimer of one heavy chain variable domain and one light chain variable domain.

[0077] The “Single-chain Fv” or “scFv” includes the VH and VL domains of an antibody, wherein these domains are present in a single polypeptide chain. In one embodiment, the Fv polypeptide further comprises a polypeptide linker between the VH and VL domains which enables the scFv to form the desired structure for antigen-binding. For a review of scFv see Pluckthun in The Pharmacology of Monoclonal Antibodies, vol.113, Rosenburg and Moore eds., Springer-Verlag, New York, pp.269-315 (1994).

[0078] The term “single domain antibody” or “sdAb” refers to a molecule in which one variable domain of an antibody specifically binds to an antigen without the presence of the other variable domain. Single domain antibodies, and fragments thereof, are described in Arabi Ghahroudi et al., FEBS Letters, 1998, 414:521-526 and Muyldermans et al., Trends in Biochem. Sci., 2001, 26:230-245, each of which is incorporated by reference in its entirety. Single domain antibodies are also known as sdAbs or nanobodies. Sdabs are fairly stable and easy to express as fusion partner with the Fc chain of an antibody (Harmsen MM, De Haard -27- IPTS / 200096106.1Attorney Docket No. ITL-013WO HJ (2007). “Properties, production, and applications of camelid single-domain antibody fragments.” Appl. Microbiol Biotechnol.77(1): 13-22). As used herein, the term “single- chain” refers to a molecule comprising amino acid monomers linearly linked by peptide bonds. In a particular such embodiment, the C-terminus of the Fab light chain is connected to the N-terminus of the Fab heavy chain in the single-chain Fab molecule. As described in more detail herein, an scFv has a variable domain of light chain (VL) connected from its C- terminus to the N-terminal end of a variable domain of heavy chain (VH) by a polypeptide chain. Alternately the scFv comprises of polypeptide chain where in the C-terminal end of the VH is connected to the N-terminal end of VL by a polypeptide chain.

[0079] As used herein, “competition” between antibodies and / or antigen binding fragments thereof signifies that both antibodies or antigen-binding fragments thereof bind to the same, or overlapping, epitope of a P2X3 protein, P2X2 protein, or a P2X2 / P2X3 heterodimer (e.g., as determined by a competitive binding assay, by any of the methods well known to those of skill in the art).

[0080] As used herein, the term “gene” refers to the basic unit of heredity, consisting of a segment of DNA arranged along a chromosome, which codes for a specific protein or segment of protein. A gene typically includes a promoter, a 5' untranslated region, one or more coding sequences (exons), optionally introns, and a 3' untranslated region. The gene may further comprise a terminator, enhancers and / or silencers.

[0081] The term “sufficient amount” means an amount sufficient to produce a desired effect, e.g., an amount sufficient to bind a target antigen, in vivo or in vitro.

[0082] The term “therapeutically effective amount” is an amount that is effective to ameliorate a symptom of a disease.

[0083] As used herein, the term “treating” includes any effect, e.g., lessening, reducing, modulating, ameliorating or eliminating, that results in the improvement of the condition, disease, disorder, and the like, or ameliorating a symptom thereof.

[0084] The term “composition” refers to a mixture that contains, e.g., an engineered cell or protein contemplated herein. In some embodiments, the composition may contain additional components, such as adjuvants, stabilizers, excipients, and the like. The term “composition” or “pharmaceutical composition” refers to a preparation which is in such form as to permit the biological activity of an active ingredient contained therein to be effective in treating a -28- IPTS / 200096106.1Attorney Docket No. ITL-013WO subject, and which contains no additional components which are unacceptably toxic to the subject in the amounts provided in the pharmaceutical composition.

[0085] The term “ameliorating” refers to any therapeutically beneficial result in the treatment of a disease state, e.g., a cancer disease state, lessening in the severity or progression, remission, or cure thereof.

[0086] As used herein, the term “effective amount” refers to the amount of a compound (e.g., a compositions described herein, cells described herein) sufficient to effect beneficial or desired results. An effective amount can be administered in one or more administrations, applications or dosages and is not intended to be limited to a particular formulation or administration route.

[0087] The term “encode” refers to protein coding sequences or non-protein coding sequences. Non-protein coding sequences include, but are not limited to, short hairpin RNA (shRNA), small interfering RNA (siRNA), double stranded RNA (dsRNA), or antisense oligonucleotides.

[0088] As used, the term “encoding” refers to a sequence of nucleic acids which codes for a protein or polypeptide of interest. The nucleic acid sequence may be found within either a molecule of DNA or RNA. In preferred embodiments, the molecule is a DNA molecule. In other preferred embodiments, the molecule is an RNA molecule. When present as an RNA molecule, it will comprise sequences which direct the ribosomes of the host cell to start translation (e.g., a start codon, AUG) and direct the ribosomes to end translation (e.g., a stop codon). Between the start codon and stop codon is an open reading frame (ORF). Such terms are known to one of ordinary skill in the art.

[0089] The term percent “identity,” in the context of two or more nucleic acid or polypeptide sequences, refers to two or more sequences or subsequences that have a specified percentage of nucleotides or amino acid residues that are the same, when compared and aligned for maximum correspondence, as measured using one of the sequence comparison algorithms described below (e.g., BLASTP and BLASTN or other algorithms available to persons of skill) or by visual inspection. Depending on the application, the percent “identity” can exist over a region of the sequence being compared, e.g., over a functional domain, or, alternatively, exist over the full length of the two sequences to be compared.

[0090] For sequence comparison, typically one sequence acts as a reference sequence to which test sequences are compared. When using a sequence comparison algorithm, test and -29- IPTS / 200096106.1Attorney Docket No. ITL-013WO reference sequences are input into a computer, subsequence coordinates are designated, if necessary, and sequence algorithm program parameters are designated. The sequence comparison algorithm then calculates the percent sequence identity for the test sequence(s) relative to the reference sequence, based on the designated program parameters.

[0091] Optimal alignment of sequences for comparison can be conducted, e.g., by the local homology algorithm of Smith & Waterman, Adv. Appl. Math.2:482 (1981), by the homology alignment algorithm of Needleman & Wunsch, J. Mol. Biol.48:443 (1970), by the search for similarity method of Pearson & Lipman, Proc. Nat'l. Acad. Sci. USA 85:2444 (1988), by computerized implementations of these algorithms (GAP, BESTFIT, FASTA, and TFASTA in the Wisconsin Genetics Software Package, Genetics Computer Group, 575 Science Dr., Madison, Wis.), or by visual inspection (see generally Ausubel et al., infra).

[0092] One example of an algorithm that is suitable for determining percent sequence identity and sequence similarity is the BLAST algorithm, which is described in Altschul et al., J. Mol. Biol.215:403-410 (1990). Software for performing BLAST analyses is publicly available through the National Center for Biotechnology Information (www.ncbi.nlm.nih.gov / ).

[0093] As used herein, the term “operably linked” or “operatively linked” refers to the binding of a nucleic acid sequence to a single nucleic acid fragment such that one function is affected by the other. For example, if a promoter is capable of affecting the expression of a coding sequence or functional RNA (i.e., the coding sequence or functional RNA is under transcriptional control by the promoter), the promoter is operably linked thereto. Coding sequences can be operably linked to control sequences in both sense and antisense orientation. Two coding DNA sequences are said to be “operably linked” if the linkage results in a continuously translatable sequence without alteration or interruption of the triplet reading frame. A DNA coding sequence is operably linked to a gene expression element if the linkage results in the proper function of that gene expression element to result in expression of the coding sequence.

[0094] The term “purified” with referenced to an antibody refers to an antibody that is substantially free of other material that associates with the molecule in its natural environment. For instance, a purified protein is substantially free of the cellular material or other proteins from the cell or tissue from which it is derived. The term refers to preparations where the isolated protein is sufficiently pure to be analyzed, or at least 70% to 80% (w / w) -30- IPTS / 200096106.1Attorney Docket No. ITL-013WO pure, at least 80%-90% (w / w) pure, 90-95% pure; and, at least 95%, 96%, 97%, 98%, 99%, or 100% (w / w) pure. In some embodiments, the antibody is purified.

[0095] The terms “vector” and “plasmid” are used interchangeably and as used herein refer to polynucleotide vehicles useful to introduce genetic material into a cell. Vectors can be linear or circular. Vectors can integrate into a target genome of a host cell or replicate independently in a host cell. Vectors can comprise, for example, an origin of replication, a multicloning site, and / or a selectable marker. An expression vector typically comprises an expression cassette. Vectors and plasmids include, but are not limited to, integrating vectors, prokaryotic plasmids, eukaryotic plasmids, plant synthetic chromosomes, episomes, cosmids, and artificial chromosomes.

[0096] The term “in vivo” refers to processes that occur in a living organism.

[0097] The term “in situ” refers to processes that occur in a living cell growing separate from a living organism, e.g., growing in tissue culture.

[0098] As used herein, the term “ex vivo” generally includes experiments or measurements made in or on living tissue, preferably in an artificial environment outside the organism, preferably with minimal differences from natural conditions.

[0099] The terms “increase” and “activate” refer to an increase of 10%, 20%, 30%, 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 2-fold, 3-fold, 4-fold, 5-fold, 10-fold, 20-fold, 50-fold, 100-fold, or greater in a recited variable.

[0100] The term “mammal” as used herein includes both humans and non-humans and include but is not limited to humans, non-human primates, canines, felines, murines, bovines, equines, and porcines.

[0101] The terms “modulate” and “modulation” refer to reducing or inhibiting or, alternatively, activating or increasing, a recited variable.

[0102] The terms “protein,” “polypeptide,” and “peptide” are used herein interchangeably.

[0103] The terms “reduce” and “inhibit” refer to a decrease of 10%, 20%, 30%, 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 2-fold, 3-fold, 4-fold, 5-fold, 10-fold, 20-fold, 50- fold, 100-fold, or greater in a recited variable.

[0104] As used herein, the term “subject” refers to a mammalian subject. Exemplary subjects include humans, monkeys, dogs, cats, mice, rats, cows, horses, camels, goats, rabbits, pigs and sheep. In certain embodiments, the subject is a human. In some -31- IPTS / 200096106.1Attorney Docket No. ITL-013WO embodiments the subject has a disease or condition that can be treated with an engineered cell provided herein or population thereof. In some aspects, the disease or condition is a cancer.

[0105] As used herein and unless otherwise indicated, the term “about” is intended to mean ± 5% of the value it modifies. Thus, about 100 means 95 to 105. P2X3 / P2X2 Binding Domains

[0106] In some aspects, provided herein are antibodies or antigen binding fragments thereof that bind to P2X3, P2X2, and / or a P2X3 / P2X2 heterodimer. In some aspects, provided herein are means for specifically binding to P2X3, P2X2, and / or a P2X3 / P2X2 heterodimer. In some embodiments, the means for binding to P2X3, P2X2, and / or a P2X3 / P2X2 comprises an antibody or antigen-binding fragment provided herein. In some embodiments, an antibody or antigen-binding fragment or equivalent thereof comprises a means for binding P2X3, P2X2, and / or a P2X3 / P2X2 heterodimer, optionally binding a human P2X3, P2X2, and / or a P2X3 / P2X2 heterodimer in the region(s) of human P2X3, P2X2, and / or a P2X3 / P2X2 heterodimer bound by the antibodies of the present disclosure (e.g., as described in the Examples below). In some embodiments, the means binds a P2X3 protein. In some embodiments, the means binds a human P2X3 protein. In some embodiments, the means binds an amino acid sequence of SEQ ID NO: 148 or 147. In some embodiments, the means is an antibody or antigen-binding fragment or equivalent thereof (e.g., a full length antibody or a F(ab')2 fragment, a Fab fragment, a single chain variable fragment (scFv), and a single domain antibody (sdAb), or a functional fragment thereof). In some embodiments, the means for binding P2X3, P2X2, and / or a P2X3 / P2X2 heterodimer includes the antibodies and antigen-binding fragments or equivalents thereof described herein.

[0107] As used herein, the term “P2X3” can also be substituted with the term “P2RX3.” In some embodiments, P2X3 comprises an amino acid sequence comprising SEQ ID NO: 148, which is shown in the table below. In some embodiments, the antibody binds to P2X3. In some embodiments, the antibodies bind to P2X2 and / or a P2X2 / P2X3 heterodimer. The sequences of P2X2 and / or a P2X2 / P2X3 heterodimer are also known. In some embodiments, the antibody binds with a dissociation constant (KD) of 10-7M or less, and binds to the predetermined antigen with a KDthat is at least two-fold less than its KDfor binding to a non- specific antigen (e.g., BSA, casein, or another non-specific polypeptide) other than the predetermined antigen. The phrases “an antibody recognizing P2X3” and “an antibody specific for P2X3” are used interchangeably herein with the term “an antibody which binds -32- IPTS / 200096106.1Attorney Docket No. ITL-013WO immunospecifically to P2X3.” Therefore, in some embodiments, the antibody binds to one or more of P2X2, P2X3, or a P2X2 / P2X3 heterodimer. Sequences of human P2X3 and P2X2 proteins are provided in Table 3 Table 3: P2X2 and P2X3 Protein Sequences Protein Amino Acid Sequence P2X2 (Isoform D)MAAAQPKYPAGATARRLARGCWSALWDYETPKVIVVRNRRLGVLYRAVQLL P G H L Y N C F V Q C R Q D K :, embodiments, the antibody binds to amino acids of an epitope of the P2X3. In some embodiments, the antibody binds to one or more of a P2X3 protein, P2X2 protein, or a P2X2 / P2X3 heterodimer. In some embodiments, the antibody binds specifically to the proteins and antigens described herein.

[0109] In some embodiments, the antibody comprises a sequence selected from the group consisting of SEQ ID NOs: 1-146 and the amino acid sequences ofDND,WND, DNT,SNN, SND, DST, QNN,SSD, and NND, or an antigen binding fragment thereof, or any combination thereof. The combination can be any combination of CDR sequences described herein or sequences that have at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity thereto. For example, the heavy chain CDRs of clone 1 can be combined with the light chain CDRs of clone 2. In some embodiments, the fragments of the CDRs can also be combined in any manner. -33- IPTS / 200096106.1Attorney Docket No. ITL-013WO

[0110] Table 4 provides exemplary amino acid sequences of antibody heavy chain variable domains (VHs) and light chain variable domains (VLs) that, in combination, bind to a P2X3 protein, a P2X2 protein, or a P2X2 / P2X3 heterodimer. In some embodiments, the antibody comprises one or more of the sequences for the specific clones listed in Table 4. In some embodiments, the antibody comprises the sequences of one of the clones listed in Table 4. Table 4: P2X2 / P2X3-Binding Antibody Sequences Clone VH Sequence VL Sequence CDRs (non-Kabat) CDRs (Kabat) 1 AVTLDESGGGLQT VQAAVTQPASVSA HCDR1: GFTFSSVN (SEQ HCDR1: SVNML (SEQ ID Q Q-34- IPTS / 200096106.1Attorney Docket No. ITL-013WO LCDR2: DNT LCDR2: DNTNRPS (SEQ LCDR3: GTTSTDAGI ID NO: 36) L DR Q Q I Q I- - IPTS / 200096106.1Attorney Docket No. ITL-013WO APGKGLEWVGVIS KSPGSAPVTLVYS HCDR2: ISTDGSYT (SEQ HCDR2: TDGSYTNYGAAVK NDKRPSDIPSRFS ID NO: 41) VISTDGSYTNYGAAVKG GRATISRDNGQST GSRSGSTATLTIT (SEQ ID NO: 58) H DR I V D D- - IPTS / 200096106.1Attorney Docket No. ITL-013WO CGDGTWCAAGTID TLTVL LCDR1: SGGGSSYY (SEQ A (SEQ ID NO: 76) AWGHGTEVIVSS (SEQ ID NO: 68) ID NO: 72) (SEQ ID NO: 79) LCDR1: SGGGSSYYG L DR2 Q I-37- IPTS / 200096106.1Attorney Docket No. ITL-013WO (SEQ ID NO: 110) 16AVTLDESGGGLQT LVQAALTQPASVS HCDR1: GFTFSSYG (SEQ HCDR1: SYGMG (SEQ ID P ALLVKA ANL TVKIT Q I-38- IPTS / 200096106.1Attorney Docket No. ITL-013WO VRLQLNNLRAEDT GVQVEDEAVYFCG ARSSYECAWSCGAGNIDA HCDR3: AIYFCARSSYECA SGDSSYVGLFGAG (SEQ ID NO: 130) SSYECAWSCGAGNIDA WSCGAGNIDAWGH TTLTVL LCDR1 (SEQ ID NO: 131) I D-39- IPTS / 200096106.1Attorney Docket No. ITL-013WO (SEQ ID NO: 73) ID NO: 78) LCDR3: ATTDSSNTAT E ID N 7or more of the amino acid sequences indicated as heavy chain CDRs in Table 4. In some embodiments, the antibody comprises a light chain CDR comprising one or more of the amino acid sequences indicated as light chain CDRs in Table 4. The antibodies listed in Table 4 were derived from Chicken IgY antibodies. As repeatedly discussed herein, these antibodies can be modified to yield human IgG antibodies or other types of antibodies as desired. In some embodiments, the antibody comprises one or more amino acid sequences of SEQ ID NOs: 1-146 and the amino acid sequences of DND, WND, DNT,SNN, SND, DST, QNN, SSD, and NND, an antigen binding fragment thereof, or a human IgG variant thereof. “A human IgG variant thereof” refers to an antibody that has been modified to be a human IgG when the starting antibody is not a human IgG antibody.

[0112] In some embodiments, the antibody or antigen-binding fragment that binds to a P2X3 protein, a P2X2 protein, or a P2X2 / P2X3 heterodimer comprises a heavy chain variable domain (VH) comprising a heavy chain complementarity determining region 1 (HCDR1), a heavy chain complementarity determining region 2 (HCDR2), and a heavy chain complementarity determining region 3 (HCDR3), and a light chain variable domain (VL) comprising a light chain complementarity determining region 1 (LCDR1), a light chain complementarity determining region 2 (LCDR2), and a light chain complementarity determining region (LCDR3), wherein the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are each from a clone listed in Table 4. In some embodiments, the antibody or antigen-binding fragment competes with an antibody or antigen binding fragment thereof comprising the amino acid sequence of a VH and a VL of a clone listed in Table 4 for binding to a P2X3 protein, P2X2 protein, or a P2X2 / P2X3 heterodimer.

[0113] In some embodiments, the antibody or antigen-binding fragment that binds to a P2X3 protein, P2X2 protein, or a P2X2 / P2X3 heterodimer comprises a VH and a VL each comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at -40- IPTS / 200096106.1Attorney Docket No. ITL-013WO least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence of a VH and a VL of a clone listed in Table 4. In some embodiments, the antibody or antigen-binding fragment competes with an antibody or antigen binding fragment thereof comprising the amino acid sequence of a VH and a VL of a clone listed in Table 4 for binding to a P2X3 protein, P2X2 protein, or a P2X2 / P2X3 heterodimer.

[0114] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 1. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 3, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 4, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 5, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 6, an LCDR2 comprising the amino acid sequence ofDND, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 7. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 8, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 9, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 10, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 11, an LCDR2 comprising the amino acid sequence of set forth in SEQ ID NO: 12, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 7. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 1 and a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 2. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 1 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 2. -41- IPTS / 200096106.1Attorney Docket No. ITL-013WO

[0115] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 2. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 15, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 16, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 17, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 18, an LCDR2 comprising the amino acid sequence ofWND, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 19. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 20, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 21, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 22, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 23, an LCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 24, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 19. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 13 and a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 14. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 13 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 14.

[0116] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 3. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 27, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 28, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 29, -42- IPTS / 200096106.1Attorney Docket No. ITL-013WO and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 30, an LCDR2 comprising the amino acid sequence ofDNT, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 31. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 32, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 33, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 34, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 35, an LCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 36, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 31. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 25 and a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 26. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 25 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 26.

[0117] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 4. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 27, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 28, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 29, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 30, an LCDR2 comprising the amino acid sequence ofDNT, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 31. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 32, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 33, and an -43- IPTS / 200096106.1Attorney Docket No. ITL-013WO HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 34, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 35, an LCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 36, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 31. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 37 and a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 26. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 37 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 26.

[0118] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 5. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 40, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 41, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 42, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 43, an LCDR2 comprising the amino acid sequence ofSNN, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 44. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 45, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 46, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 47, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 48, an LCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 49, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 44. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, -44- IPTS / 200096106.1Attorney Docket No. ITL-013WO at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 38 and a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 39. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 38 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 39.

[0119] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 6. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 40, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 41, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 42, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 43, an LCDR2 comprising the amino acid sequence ofSNN, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 44. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 45, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 46, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 47, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 48, an LCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 49, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 44. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 38 and a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 50. In some embodiments, the antibody -45- IPTS / 200096106.1Attorney Docket No. ITL-013WO or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 38 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 50.

[0120] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 7. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 53, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 41, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 54, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 55, an LCDR2 comprising the amino acid sequence ofSND, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 56. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 57, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 58, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 59, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 60, an LCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 61, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 56. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 51 and a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 52. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 51 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 52.

[0121] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 8. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 -46- IPTS / 200096106.1Attorney Docket No. ITL-013WO heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 53, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 41, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 54, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 64, an LCDR2 comprising the amino acid sequence ofSND, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 65. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 57, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 58, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 59, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 66, an LCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 61, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 65. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 62 and a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 63. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 62 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 63.

[0122] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 10. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 69, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 70, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 71, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 72, an LCDR2 comprising the amino acid sequence ofDST, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 73. In some embodiments, the antibody or -47- IPTS / 200096106.1Attorney Docket No. ITL-013WO antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 74, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 75, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 76, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 77, an LCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 78, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 73. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 67 and a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 68. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 67 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 68.

[0123] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 12. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 69, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 70, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 71, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 72, an LCDR2 comprising the amino acid sequence ofDST, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 73. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 74, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 80, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 76, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 77, an LCDR2 comprising the amino acid sequence of 78, and an LCDR3 comprising the amino -48- IPTS / 200096106.1Attorney Docket No. ITL-013WO acid sequence set forth in SEQ ID NO: 73. In some embodiments, the antibody or antigen- binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 79 and a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 68. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 79 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 68.

[0124] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 13. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 83, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 84, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 85, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 86, an LCDR2 comprising the amino acid sequence ofQNN, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 87. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 88, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 89, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 90, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 91, an LCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 92, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 87. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 81 and a VL comprising an amino acid sequence at least -49- IPTS / 200096106.1Attorney Docket No. ITL-013WO 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 82. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 81 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 82.

[0125] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 14. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 95, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 96, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 97, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 98, an LCDR2 comprising the amino acid sequence ofSND, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 99. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 101, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 102, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 103, an LCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 61, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 99. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 93 and a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 94. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 93 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 94. -50- IPTS / 200096106.1Attorney Docket No. ITL-013WO

[0126] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 15. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 106, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 107, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 108, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 109, an LCDR2 comprising the amino acid sequence ofSND, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 110. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 111, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 112, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 113, an LCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 114, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 110. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 104 and a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 105. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 104 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 105.

[0127] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 16. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 95, an HCDR2 comprising the amino acid sequence set forth in SEQ ID -51- IPTS / 200096106.1Attorney Docket No. ITL-013WO NO: 96, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 108, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 98, an LCDR2 comprising the amino acid sequence ofSSD, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 117. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 118, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 112, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 103, an LCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 119, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 117. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 115 and a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 116. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 115 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 116.

[0128] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 17. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 106, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 107, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 108, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 121, an LCDR2 comprising the amino acid sequence ofDNT, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 122. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set -52- IPTS / 200096106.1Attorney Docket No. ITL-013WO forth in SEQ ID NO: 100, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 111, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 112, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 123, an LCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 36, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 122. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 104 and a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 120. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 104 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 120.

[0129] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 18. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 106, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 107, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 108, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 126, an LCDR2 comprising the amino acid sequence ofSND, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 110. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 111, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 112, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 127, an LCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 61, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 110. In some -53- IPTS / 200096106.1Attorney Docket No. ITL-013WO embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 124 and a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 125. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 124 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 125.

[0130] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 19. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 95, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 96, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 130, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 98, an LCDR2 comprising the amino acid sequence ofSND, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 99. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 101, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 131, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 103, an LCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 61, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 99. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 128 and a VL comprising an amino acid sequence at least -54- IPTS / 200096106.1Attorney Docket No. ITL-013WO 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 129. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 128 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 129.

[0131] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 20. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 95, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 134, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 130, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 135, an LCDR2 comprising the amino acid sequence ofNND, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 136. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 137, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 131, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 138, an LCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 139, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 136. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 132 and a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 133. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 132 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 133. -55- IPTS / 200096106.1Attorney Docket No. ITL-013WO

[0132] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 21. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 106, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 107, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 130, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 126, an LCDR2 comprising the amino acid sequence ofSND, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 142. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 111, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 131, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 127, an LCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 61, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 142. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 140 and a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 141. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 140 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 141.

[0133] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 24. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 69, an HCDR2 comprising the amino acid sequence set forth in SEQ ID -56- IPTS / 200096106.1Attorney Docket No. ITL-013WO NO: 70, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 71, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 144, an LCDR2 comprising the amino acid sequence ofDST, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 73. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an HCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 74, an HCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 75, and an HCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 76, and a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 77, an LCDR2 comprising the amino acid sequence set forth in SEQ ID NO: 78, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 73. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 67 and a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to the amino acid sequence set forth in SEQ ID NO: 143. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a VH comprising the amino acid sequence set forth in SEQ ID NO: 67 and a VL comprising the amino acid sequence set forth in SEQ ID NO: 143.

[0134] In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer is or is derived from clone 25. In some embodiments, the antibody or antigen-binding fragment that binds to P2X3, P2X2, or a P2X2 / P2X3 heterodimer comprises a a VL comprising an LCDR1 comprising the amino acid sequence set forth in SEQ ID NO: 145, an LCDR2 comprising the amino acid sequence ofSND, and an LCDR3 comprising the amino acid sequence set forth in SEQ ID NO: 146. Nucleic Acids

[0135] In various embodiments, the present disclosure provides a nucleic acid encoding at least one polypeptide of the P2X3, P2X2, and / or a P2X3 / P2X2 heterodimer-binding antibody or antigen-binding fragment thereof provided herein. In certain embodiments, the nucleic acid further comprises a nucleotide sequence encoding a signal peptide that, when expressed, -57- IPTS / 200096106.1Attorney Docket No. ITL-013WO is at the N-terminus of one or more of the polypeptides. Also provided is a vector (e.g., a viral vector) comprising the nucleic acid, and a producer cell comprising the nucleic acid or vector.

[0136] The nucleic acid sequence encoding an antibody described herein can be genomic DNA or cDNA, or RNA (e.g., mRNA) which encodes at least one of the variable regions described herein. A convenient alternative to the use of chromosomal gene fragments as the source of DNA encoding the V region antigen-binding segment is the use of cDNA for the construction of chimeric immunoglobulin genes, e.g., as reported by Liu et al. (Proc. Natl. Acad. Sci., USA 84:3439 (1987) and J. Immunology 139:3521 (1987), which references are hereby entirely incorporated herein by reference. The use of cDNA requires that gene expression elements appropriate for the host cell be combined with the gene in order to achieve synthesis of the desired protein. The use of cDNA sequences is advantageous over genomic sequences (which contain introns), in that cDNA sequences can be expressed in bacteria or other hosts which lack appropriate RNA splicing systems.

[0137] In certain embodiments, the nucleic acid is a DNA molecule (e.g., a cDNA molecule). In certain embodiments, the nucleic acid further comprises an expression control sequence (e.g., promoter and / or enhancer) operably linked to the nucleic acid sequence encoding the antibody or antigen-binding fragment. The vector can be a viral vector (e.g., AAV vector, lentiviral vector, or adenoviral vector) or a non-viral vector (e.g., plasmid).

[0138] RNA or DNA can be introduced into target cells using any of a number of different methods, for instance, commercially available methods, which include, but are not limited to, electroporation, cationic liposome mediated transfection using lipofection, polymer encapsulation, peptide mediated transfection, or biolistic particle delivery systems such as “gene guns” (see, for example, Nishikawa, et al. Hum Gene Ther., 12(8):861-70 (2001)).

[0139] In some embodiments, a cDNA encoding a V region antigen-binding segment able to detect, bind, to or neutralize a P2X3 antigen can be provided using known methods based on the use of the amino acid sequences provided herein. Because the genetic code is degenerate, more than one codon can be used to encode a particular amino acid (Watson, et al., infra). Using the genetic code, one or more different oligonucleotides can be identified, each of which would be capable of encoding the amino acid. The probability that a particular oligonucleotide will, in fact, constitute the actual XXX-encoding sequence can be estimated by considering abnormal base pairing relationships and the frequency with which a particular codon is actually used (to encode a particular amino acid) in eukaryotic or prokaryotic cells -58- IPTS / 200096106.1Attorney Docket No. ITL-013WO expressing an antibody or fragment. Such “codon usage rules” are disclosed by Lathe, et al., J. Molec. Biol.183:112 (1985). Using the “codon usage rules” of Lathe, a single oligonucleotide, or a set of oligonucleotides, that contains a theoretical “most probable” nucleotide sequence capable of encoding an antibody variable or constant region sequences is identified.

[0140] Genes encoding human immunoglobulin C regions can be obtained from human cells by standard cloning techniques (Sambrook, et al. (Molecular Cloning: A Laboratory Manual, 2nd Edition, Cold Spring Harbor Press, Cold Spring Harbor, N.Y. (1989) and Ausubel et al., eds. Current Protocols in Molecular Biology (1987-1993)). Human C region genes are readily available from known clones containing genes representing the two classes of L chains, the five classes of H chains and subclasses thereof. Chimeric antibody fragments, such as F(ab')2 and Fab, can be prepared by designing a chimeric H chain gene which is appropriately truncated. For example, a chimeric gene encoding an H chain portion of an F(ab')2 fragment would include DNA sequences encoding the CH1 domain and hinge region of the H chain, followed by a translational stop codon to yield the truncated molecule.

[0141] In some embodiments, the antibodies, fragments and regions of the antibodies described herein are produced by cloning DNA segments encoding the H and L chain antigen-binding regions of a P2X3 antigen specific antibody, and joining these DNA segments to DNA segments encoding CH and CL regions, respectively, to produce murine, human or chimeric immunoglobulin-encoding genes.

[0142] Thus, in some embodiments, a fused chimeric gene is created which comprises a first DNA segment that encodes at least the antigen-binding region of non-human origin, such as a functionally rearranged V region with joining (J) segment, linked to a second DNA segment encoding at least a part of a human C region.

[0143] Therefore, cDNA encoding the antibody V and C regions, the method of producing the chimeric antibody according to some of the embodiments described herein can involve several steps, as exemplified below: 1. isolation of messenger RNA (mRNA) from the cell line producing an anti- P2X3 antigen antibody and from optional additional antibodies supplying heavy and light constant regions; cloning and cDNA production therefrom; 2. preparation of a full length cDNA library from purified mRNA from which the appropriate V and / or C region gene segments of the L and H chain genes can be: (i) identified with appropriate probes, (ii) sequenced, and (iii) made compatible with a C or V gene segment -59- IPTS / 200096106.1Attorney Docket No. ITL-013WO from another antibody for a chimeric antibody; 3. Construction of complete H or L chain coding sequences by linkage of the cloned specific V region gene segments to cloned C region gene, as described above; 4. Expression and production of L and H chains in selected hosts, including prokaryotic and eukaryotic cells to provide murine-murine, human-murine, human-human or human murine antibodies.

[0144] Expression vehicles can include plasmids or other vectors. Preferred among these are vehicles carrying a functionally complete human CHor CLchain sequence having appropriate restriction sites engineered so that any VH or VL chain sequence with appropriate cohesive ends can be easily inserted therein. Human CHor CLchain sequence-containing vehicles can thus serve as intermediates for the expression of any desired complete H or L chain in any appropriate host. Administration, Compositions, and Kits Comprising the Antibodies

[0145] Whereas, an isolated antibody binds an epitope on a P2X3 protein, or other protein described herein, and displays in vitro and / or in vivo P2X3 inhibiting or therapeutic activities, the antibodies or antigen binding fragments thereof, capable of inhibiting P2X3 function and symptoms, are suitable both as therapeutic and prophylactic agents for treating or preventing P2X3-associated conditions in humans and animals. These conditions include the feeling of pain.

[0146] In general, use will comprise administering a therapeutically or prophylactically effective amount of one or more monoclonal antibodies or antigen binding fragments of the antibodies described herein to a susceptible subject or to one exhibiting a condition in which P2X3 is known to have caused the pathology (e.g., pain) observed. Any active form of the antibody can be administered, including, but not limited to Fab and F(ab')2 fragments.

[0147] As used herein, a P2X3, P2X2, or P2X2 / P2X3 associated pathology refers to conditions that are caused by the activation of a P2X3, P2X2, or P2X2 / P2X3 receptor. These conditions include, but are not limited to, pain.

[0148] In some embodiments, the antibodies used are compatible with the recipient species such that the immune response to the antibodies does not result in an unacceptably short circulating half-life or induce an immune response to the antibodies in the subject. In some embodiments, the antibodies administered exhibit some secondary functions such as binding to Fc receptors of the subject and activation of antibody dependent cell mediated cytotoxicity (ADCC) mechanisms. -60- IPTS / 200096106.1Attorney Docket No. ITL-013WO

[0149] Treatment of individuals may comprise the administration of a therapeutically effective amount of the antibodies described herein. The antibodies can be provided in a kit as described below. The antibodies can be used or administered alone or in admixture with another therapeutic, analgesic, or diagnostic agent. In providing a patient with an antibody, or fragment thereof, capable of binding to a P2X3, P2X2, or P2X2 / P2X3, or an antibody capable of protecting against P2X3, P2X2, or P2X2 / P2X3 pathology in a recipient patient, the dosage of administered agent will vary depending upon such factors as the patient's age, weight, height, sex, general medical condition, previous medical history, etc.

[0150] Suitable vehicles and their formulation and packaging are described, for example, in Remington: The Science and Practice of Pharmacy (21st ed., Troy, D. ed., Lippincott Williams & Wilkins, Baltimore, Md. (2005) Chapters 40 and 41). Additional pharmaceutical methods may be employed to control the duration of action. Controlled release preparations may be achieved through the use of polymers to complex or absorb the compounds. Another possible method to control the duration of action by controlled release preparations is to incorporate the compounds of into particles of a polymeric material such as polyesters, polyamino acids, hydrogels, poly(lactic acid) or ethylene vinylacetate copolymers. Alternatively, instead of incorporating these agents into polymeric particles, it is possible to entrap these materials in microcapsules prepared, for example, interfacial polymerization, for example, hydroxymethylcellulose or gelatin-microcapsules and poly(methylmethacylate)- microcapsules, respectively, or in colloidal drug delivery systems, for example, liposomes, albumin microspheres, microemulsions, nanoparticles, and nanocapsules or in macroemulsions.

[0151] When administering a therapeutic composition (e.g., a pharmaceutical composition containing an antibody or antigen-binding fragment), it will generally be formulated in a unit dosage injectable form (solution, suspension, emulsion). Actual dosage levels of the active ingredients in the pharmaceutical compositions described herein may be varied so as to obtain an amount of the active ingredient which is effective to achieve the desired therapeutic response for a particular patient, composition, and mode of administration, without being toxic to the subject.

[0152] The specific dose can be a uniform dose for each patient. Alternatively, a patient’s dose can be tailored to the approximate body weight or surface area of the patient. Other factors in determining the appropriate dosage can include the disease or condition to be treated or prevented, the severity of the disease, the route of administration, and the age, sex -61- IPTS / 200096106.1Attorney Docket No. ITL-013WO and medical condition of the patient. Further refinement of the calculations necessary to determine the appropriate dosage for treatment is routinely made by those skilled in the art, especially in light of the dosage information and assays disclosed herein. The dosage can also be determined through the use of known assays for determining dosages used in conjunction with appropriate dose-response data. An individual patient's dosage can be adjusted as the progress of the disease is monitored. Blood levels of the targetable construct or complex in a patient can be measured to see if the dosage needs to be adjusted to reach or maintain an effective concentration. Pharmacogenomics may be used to determine which targetable constructs and / or complexes, and dosages thereof, are most likely to be effective for a given individual (Schmitz et al., Clinica Chimica Acta 308: 43-53, 2001; Steimer et al., Clinica Chimica Acta 308: 33-41, 2001).

[0153] In general, if administering a systemic dose of the antibody, it is desirable to provide the recipient with a dosage of antibody which is in the range of from about 1 ng / kg- 100 ng / kg, 100 ng / kg-500 ng / kg, 500 ng / kg-1 ug / kg, 1 ug / kg-100 ug / kg, 100 ug / kg-500 ug / kg, 500 ug / kg-1 mg / kg, 1 mg / kg-50 mg / kg, 50 mg / kg-100 mg / kg, 100 mg / kg-500 mg / kg (body weight of recipient), although a lower or higher dosage may be administered. Dosages as low as about 1.0 mg / kg may be expected to show some efficacy. Preferably, about 5 mg / kg is an acceptable dosage, although dosage levels up to about 50 mg / kg are also preferred especially for therapeutic use. Alternatively, administration of a specific amount of the antibody may be given which is not based upon the weight of the patient such as an amount in the range of 1 ug-100 ug, 1 mg-100 mg, or 1 gm-100 gm. For example, site specific administration may be to body compartment or cavity such as intrarticular, intrabronchial, intraabdominal, intracapsular, intracartilaginous, intracavitary, intracelial, intracelebellar, intracerebroventricular, intracolic, intracervical, intragastric, intrahepatic, intramyocardial, intraosteal, intrapelvic, intrapericardiac, intraperitoneal, intrapleural, intraprostatic, intrapulmonary, intrarectal, intrarenal, intraretinal, intraspinal, intrasynovial, intrathoracic, intrauterine, intravesical, intralesional, vaginal, rectal, buccal, sublingual, intranasal, or transdermal means.

[0154] The antibody compositions described herein can be prepared for use for parenteral (subcutaneous, intramuscular or intravenous) or any other administration particularly in the form of liquid solutions or suspensions. The formulation can also be suitable for an injectable formulation. In some embodiments, the injectable formulation is sterile. In some embodiments, the injectable formulation is pyrogen free. In some embodiments, the -62- IPTS / 200096106.1Attorney Docket No. ITL-013WO formulation is free of other antibodies that bind to other antigens other than an antigen described herein.

[0155] Doses may be given once or more times daily, weekly, monthly or yearly, or even once every 2 to 20 years. Persons of ordinary skill in the art can easily estimate repetition rates for dosing based on measured residence times and concentrations of the targetable construct or complex in bodily fluids or tissues. Administration of the compositions described herein could be intravenous, intraarterial, intraperitoneal, intramuscular, subcutaneous, intrapleural, intrathecal, intracavitary, by perfusion through a catheter or by direct intralesional injection. This may be administered once or more times daily, once or more times weekly, once or more times monthly, and once or more times annually.

[0156] An antibody, capable of treating pain or other condition associated with P2X3, P2X2, or P2X2 / P2X3 activity or use to treat a P2X3, P2X2, or P2X2 / P2X3 related pathology, is intended to be provided to subjects in an amount sufficient to affect a reduction, resolution, or amelioration in the P2X3, P2X2, or P2X2 / P2X3-related symptom or pathology. Such a pathology, includes pain in a subject. An amount is said to be sufficient or a “therapeutically effective amount” to “affect” the reduction of symptoms if the dosage, route of administration, and dosing schedule of the agent are sufficient to influence such a response. Responses to antibody administration can be measured by analysis of subject's affected tissues, organs, or cells as by imaging techniques or by ex vivo analysis of tissue samples. An agent is physiologically significant if its presence results in a detectable change in the physiology of a recipient patient. In some embodiments, an amount is a therapeutically effective amount if it is an amount that can be used to treat, ameliorate or inhibit pain a subject is subject to.

[0157] The antibodies can be formulated according to known methods to prepare pharmaceutically useful compositions, whereby these materials, or their functional derivatives, are combined in admixture with a pharmaceutically acceptable carrier vehicle. The treatment may be given in a single dose schedule, or a multiple dose schedule in which a primary course of treatment may be with 1-10 separate doses, followed by other doses given at subsequent time intervals required to maintain and or reinforce the response, for example, at 1-4 months for a second dose, and if needed, a subsequent dose(s) after several months. Examples of suitable treatment schedules include: (i) 0, 1 month and 6 months, (ii) 0, 7 days and 1 month, (iii) 0 and 1 month, (iv) 0 and 6 months, or other schedules sufficient to elicit the desired responses expected to reduce disease symptoms, or reduce severity of disease. -63- IPTS / 200096106.1Attorney Docket No. ITL-013WO

[0158] Kits are also provided which are useful for carrying out embodiments described herein. The present kits comprise a first container containing or packaged in association with the above-described antibodies. The kit may also comprise another container containing or packaged in association solutions necessary or convenient for carrying out the embodiments. The containers can be made of glass, plastic or foil and can be a vial, bottle, pouch, tube, bag, etc. The kit may also contain written information, such as procedures for carrying out the embodiments or analytical information, such as the amount of reagent contained in the first container means. The container may be in another container apparatus, e.g., a box or a bag, along with the written information.

[0159] Yet another aspect provided for herein is a kit for detecting P2X3, P2X2, or P2X2 / P2X3 protein in a biological sample. The kit includes a container holding one or more antibodies which binds an epitope of P2X3, P2X2, or P2X2 / P2X3 protein and instructions for using the antibody for the purpose of binding to P2X3, P2X2, or P2X2 / P2X3 protein to form an immunological complex and detecting the formation of the immunological complex such that the presence or absence of the immunological complex correlates with presence or absence of P2X3, P2X2, or P2X2 / P2X3 protein in the sample. Examples of containers include multi-well plates which allow simultaneous detection of P2X3, P2X2, or P2X2 / P2X3 protein in multiple samples.

[0160] In some embodiments, antibodies that bind to a P2X3 protein, P2X2 protein, or a P2X2 / P2X3 heterodimer protein are provided. In some embodiments, the antibody is isolated. In some embodiments, the antibody binds to one or more of a P2X3 protein, P2X2 protein, or a P2X2 / P2X3 heterodimer protein. In some embodiments, the antibody binds specifically. In some embodiments, the antibody binds to a P2X3 protein, P2X2 protein, or a P2X2 / P2X3 heterodimer protein that is properly folded. In some embodiments, the antibody binds to a P2X3 protein, P2X2 protein, or a P2X2 / P2X3 heterodimer protein that is in a cell membrane. In some embodiments, the antibody binds to a P2X3 protein, P2X2 protein, or a P2X2 / P2X3 heterodimer protein that is in a cell membrane in an intact cell. In some embodiments, the antibody inhibits or neutralizes the function of a P2X3 protein, P2X2 protein, or a P2X2 / P2X3 heterodimer protein. As used herein, the term “neutralize” means that the activity or function of the protein is inhibited. The inhibition can be complete or partial. In some embodiments, the activity or function of the protein is inhibited at least 10, 20, 30, 40, 50, 60, 70, 80, 90, 95, or 99%. The percent inhibition can be based upon the -64- IPTS / 200096106.1Attorney Docket No. ITL-013WO function or activity of the protein in the absence of the antibody. In some embodiments, the antibody inhibits the ion transport facilitated by P2X3, P2X2, or P2X2 / P2X3.

[0161] In some embodiments, methods of treating, inhibiting or ameliorating a P2X3, P2X2, or a P2X2 / P2X3 associated pathology are provided. In some embodiments, the methods comprise administering an antibody described herein or a pharmaceutical composition described herein to a subject to treat, inhibit or ameliorate a P2X3, P2X2, or a P2X2 / P2X3 associated pathology. In some embodiments, the pathology is pain. In some embodiments, the method alleviates the symptoms of a P2X3, P2X2, or a P2X2 / P2X3 associated pain. In some embodiments, the pain is neuropathic pain. In some embodiments, the neuropathic pain is a result of peripheral nerve damage, tumor growths, or spinal misalignment (e.g., back pain). In some embodiments, the pain is inflammatory pain. In some embodiments, the inflammatory pain is caused by rheumatoid arthritis, brain swelling, and tissue damage / repair. In some embodiments, the pathology is osteoarthritis. In some embodiments, the pathology is chronic cough (e.g., chronic idiopathic cough).

[0162] In some embodiments, methods of detecting the presence or absence of a P2X3 in a sample are provided, the method comprising contacting a sample with one or more antibodies described herein detecting the binding to a P2X3 antigen by the antibody. In some embodiments, the detection of the binding indicates the presence P2X3 antigen; or the absence of the detection of the binding to the P2X3 antigen indicates the absence of the P2X3 antigen. The detecting can be done with any known method, such as using a biosensor, ELISA, sandwich assay, and the like. The detecting methods are routine. However, in some embodiments, the method comprises detecting the presence of the protein in non-denaturing conditions. The non-denaturing conditions can be used so that the protein of interest is detected in its native, or properly folded form.

[0163] In some embodiments, methods of identifying a test antibody that binds to an epitope on P2X3 protein, P2X2 protein, or a P2X2 / P2X3 heterodimer protein are provided, the method comprising contacting a test antibody with the epitope on P2X3 protein, P2X2 protein, or a P2X2 / P2X3 heterodimer protein and determining whether the test antibody binds to the epitope. In some embodiments, the determining comprises determining whether the test antibody binds to the protein and is competitively inhibited by an antibody comprising a sequence selected from the group consisting of SEQ ID NOs: 1-146. In some embodiments, the determining comprises mutating one or more residues of epitope or protein and determining binding of the test antibody to the mutated epitope, wherein if the mutation -65- IPTS / 200096106.1Attorney Docket No. ITL-013WO reduces binding of the test antibody as compared to the non-mutated epitope, the test antibody is deemed to bind to that epitope.

[0164] In some embodiments, methods of inducing an immune response against a P2X3 antigen, P2X2 antigen, or a P2X2 / P2X3 heterodimer antigen are provided, the methods comprising administering a P2X3 antigen, P2X2 antigen, or a P2X2 / P2X3 heterodimer antigen to a subject under conditions sufficient to induce an immune response. As discussed herein, in some embodiments, the methods comprise administering a lipoparticle comprising a P2X3 antigen, P2X2 antigen, or a P2X2 / P2X3 heterodimer antigen to the subject to induce the immune response. In some embodiments, antibodies produced by the immune response are isolated. The antibodies can then be cloned, isolated and / or otherwise modified as described herein. In some embodiments, the subject is a chicken. EXAMPLES

[0165] The subject matter is now described with reference to the following examples. These examples are provided for the purpose of illustration only and the claims should in no way be construed as being limited to these examples, but rather should be construed to encompass any and all variations which become evident as a result of the teaching provided herein. Those of skill in the art will readily recognize a variety of non-critical parameters that could be changed or modified to yield essentially similar results. Example 1: Generation of Antibodies that Inhibit P2X3

[0166] The P2X purinergic ion channel family consists of seven members distributed throughout the body that detect ATP in the extracellular environment released from cells in response to mechanical stress, hypoxia, inflammation, or lethal damage (reviewed in Khakh, B. S., and North, R. A. (2006). P2X receptors as cell-surface ATP sensors in health and disease. Nature 442, 527-532). Upon binding ATP, P2X ion channels open, allowing a non- selective influx of sodium and calcium ions, resulting in neuron depolarization and downstream signaling events. Functional P2X ion channels are formed by the assembly of P2X subunits in either homo- or hetero-trimers within the cellular lipid membrane (Kawate, T., et al. (2009). Crystal structure of the ATP-gated P2X(4) ion channel in the closed state. Nature 460, 592-598). The seven P2X family members range in size from 379 to 595 amino acids, with each subunit consisting of two transmembrane domains connected via a large extracellular loop containing the ATP binding site. -66- IPTS / 200096106.1Attorney Docket No. ITL-013WO

[0167] Among the seven family members, P2X3 appears to be a (if not the) primary mediator of peripheral pain triggered by ATP, owing to its selective expression in a subset of primary afferent neurons, either in its homotrimer form or P2X2 / P2X3 heterotrimer form (Chen, C. C., et al. (1995). A P2X purinoceptor expressed by a subset of sensory neurons. Nature 377, 428-431; Khakh, B. S., and North, R. A. (2006). P2X receptors as cell-surface ATP sensors in health and disease. Nature 442, 527-532; Lewis, C., et al. (1995). Coexpression of P2X2 and P2X3 receptor subunits can account for ATP-gated currents in sensory neurons. Nature 377, 432-435). P2X3 is localized almost exclusively on the peripheral and central terminals of unmyelinated C-fiber and thinly myelinated Aδ sensory neurons. Studies in P2X3 knock-out mice have shown that the lack of P2X3 greatly reduces mechanical allodynia (Cockayne, D. A., et al. (2000). Urinary bladder hyporeflexia and reduced pain-related behaviour in P2X3-deficient mice. Nature 407, 1011-1015; Souslova, V., et al. (2000). Warm-coding deficits and aberrant inflammatory pain in mice lacking P2X3 receptors. Nature 407, 1015-1017), indicating that P2X3 is involved in chronic pain following nerve injury or inflammation. Additional evidence for the important role of P2X3 in chronic pain has been obtained in rats treated with antisense sequences to lower P2X3 expression (Barclay, J. et al. (2002). Functional downregulation of P2X3 receptor subunit in rat sensory neurons reveals a significant role in chronic neuropathic and inflammatory pain. J Neurosci 22, 8139-8147; Dorn, G., et al. (2004). siRNA relieves chronic neuropathic pain. Nucleic Acids Res 32, e49; Honore, P., et al. Analgesic profile of intrathecal P2X(3) antisense oligonucleotide treatment in chronic inflammatory and neuropathic pain states in rats. Pain 99, 11-19), as well as in rats given pharmacological inhibitors of P2X3 (Jarvis, M. F., et al. (2002). A-317491, a novel potent and selective non-nucleotide antagonist of P2X3 and P2X2 / 3 receptors, reduces chronic inflammatory and neuropathic pain in the rat. Proc Natl Acad Sci U S A 99, 17179-17184; Nakagawa, T., et al. (2007). Intrathecal administration of ATP produces long-lasting allodynia in rats: differential mechanisms in the phase of the induction and maintenance. Neuroscience 147, 445-455; Tsuda, M., et al. (2000). Mechanical allodynia caused by intraplantar injection of P2X receptor agonist in rats: involvement of heteromeric P2X2 / 3 receptor signaling in capsaicin-insensitive primary afferent neurons. J Neurosci 20, RC90).

[0168] P2X3 biologics may offer the greatest possibility of successfully, selectively, and potently targeting P2X3. Inhibitory antibodies benefit from high bioavailability and could specifically target the less conserved extracellular regions of P2X3, but have not previously -67- IPTS / 200096106.1Attorney Docket No. ITL-013WO been generated due to the difficulty of isolating conformational, inhibitory antibodies against this ion channel, as is the case for most membrane proteins which are hydrophobic and difficult to express and purify at high concentrations while retaining native conformation. The present antibodies and the ability to generate a conformationally dependent antibody against P2X3 was surprising in view of the difficulty others failures.

[0169] Prior to the present examples, inhibitory MAbs against P2X3 were difficult to derive using traditional methods.

[0170] Monoclonal antibodies (MAbs) that bind conformation-dependent (non-linear) epitopes a valuable type of MAb for therapeutic, diagnostic, and research applications because they can block critical structural and functional sites on a target protein that polyclonal antibodies, intracellular-epitope antibodies, and linear-epitope antibodies typically cannot access. For example, >95% of the inhibitory MAbs against GPCRs are conformational in nature. However, conformation-dependent MAbs against multiple-spanning membrane proteins are some of the most difficult MAbs to generate because, unlike soluble proteins, most membrane proteins are dependent on a lipid environment to maintain their native tertiary and quaternary (oligomeric) structures. Thus, to derive inhibitory MAbs that recognize conformational extracellular structures, membrane proteins must be presented in their native conformation and orientation. Conventional immunization approaches for membrane proteins using peptides, purified proteins, membrane preparations, or whole cells are limited in their ability to derive conformation-dependent, inhibitory MAbs (reviewed in Banik, S. S. R., and Doranz, B. J. (2009). Antibody Strategies for Membrane Protein Targets. In Drug Discovery & Development, pp.14-16.).

[0171] In this example, we have demonstrated the ability of lipoparticles to generate high titer antibody responses against a P2X3 target. Immunizations of chickens with lipoparticles containing the ion channel P2X3 resulted in sera which demonstrated strong reactivity (>1:12,800 serum dilution) against surface expressed P2X3 by flow cytometry, but not to control cells (FIG.1).

[0172] Using highly responsive animals, individual monoclonal antibodies against P2X3 from reactive animals (FIG.2) using B-cell selection (Crystal Biosciences) were isolated. Each MAb demonstrated high specificity, reacting with receptor-positive cells 5 to 100 fold more than the same cells transfected with a control receptor. Most importantly, each MAb -68- IPTS / 200096106.1Attorney Docket No. ITL-013WO was reactive against the native membrane protein on the surface of human cells (as detected by flow cytometry and immunofluorescence).

[0173] Lipoparticles containing P2X3 were captured onto the surface of biosensor tips, and antibody binding demonstrated specificity and dose-response kinetics (FIG.3, Left Panel), indicating that detailed binding measurements (ka, kd, and KD) can be obtained for each P2X3 MAb isolated for use in MAb selection and engineering. P2X3 MAbs were also characterized by western blot (FIG.3, Right Panel), with greater than half of those characterized to date (11 / 18) recognizing conformational epitopes and thus that could not have been isolated using peptides, denatured proteins, or recombinant protein fragments.

[0174] Three P2X3 MAbs were able to prevent P2X3 cation conductance in response to ATP (FIG.4, Left and Right Panels). These inhibitory P2X3 MAbs (converted into chimeric-human Fc format) demonstrate >10 fold signal-to-background reactivity, represent diverse CDR sequences, and recognize conformational structures of the native ion channel on the cell surface, the first such MAbs against any of the P2X family members. The sequences of the antibodies are described herein. These antibodies are expected to be able to treat pain. Example 2: Antibody Competition Assay

[0175] Competition assays are performed to determine whether an antibody binds to the same epitope as, or competes for binding with an antibody or antigen-binding fragment thereof that binds a P2X3 protein, P2X2 protein, or a P2X2 / P2X3 heterodimer (e.g., an antibody or antigen binding fragment thereof comprising the amino acid sequence of a VH and a VL of a clone listed in Table 4). Exemplary competition assays include immunoassays (e.g., ELISA assays, RIA assays), surface plasmon resonance (e.g., BIAcore analysis), bio- layer interferometry, and flow cytometry.

[0176] Typically, a competition assay involves the use of an antigen (e.g., a P2X3 protein, P2X2 protein, or a P2X2 / P2X3 heterodimer) bound to a solid surface or expressed on a cell surface, a test antibody or antigen-binding fragment thereof and a reference antibody (e.g., an antibody or antigen binding fragment thereof comprising the amino acid sequence of a VH and a VL of a clone listed in Table 4). The reference antibody is labeled, and the test antibody is unlabeled. Competitive inhibition is measured by determining the amount of labeled reference antibody bound to the solid surface or cells in the presence of the test antibody. Usually, the test antibody is present in excess (e.g., 1×, 5×, 10×, 20×, or 100×). Antibodies identified by competition assay (e.g., competing antibodies) include antibodies -69- IPTS / 200096106.1Attorney Docket No. ITL-013WO binding to the same epitope, or similar (e.g., overlapping) epitopes, as the reference antibody, and antibodies binding to an adjacent epitope sufficiently proximal to the epitope bound by the reference antibody for steric hindrance to occur.

[0177] A competition assay is conducted in both directions to ensure that the presence of the label does not interfere or otherwise inhibit binding. For example, in the first direction the reference antibody is labeled, and the test antibody is unlabeled, and in the second direction, the test antibody is labeled, and the reference antibody is unlabeled.

[0178] A test antibody competes with the reference antibody for specific binding to the antigen if an excess of one antibody (e.g., 1×, 5×, 10×, 20× or 100×) inhibits binding of the other antibody, e.g., by at least 50%, 75%, 90%, 95% or 99% as measured in a competitive binding assay.

[0179] Two antibodies are determined to bind to the same epitope if essentially all amino acid mutations in the antigen that reduce or eliminate binding of one antibody reduce or eliminate binding of the other. Two antibodies are determined to bind to overlapping epitopes if only a subset of the amino acid mutations that reduce or eliminate binding of one antibody reduce or eliminate binding of the other.

[0180] The disclosures of each and every patent, patent application, publication, and accession number cited herein are hereby incorporated herein by reference in their entirety.

[0181] While present disclosure has been disclosed with reference to various embodiments, it is apparent that other embodiments and variations of these may be devised by others skilled in the art without departing from the true spirit and scope of the disclosure. The appended claims are intended to be construed to include all such embodiments and equivalent variations. -70- IPTS / 200096106.1

Claims

Attorney Docket No. ITL-013WO WHAT IS CLAIMED IS:

1. An isolated antibody or antigen-binding fragment thereof that binds to a P2X3 protein, a P2X2 protein, or a P2X2 / P2X3 heterodimer protein.

2. The isolated antibody or antigen binding fragment of claim 1, wherein the isolated antibody or antigen binding fragment binds to a P2X3 protein, a P2X2 protein, or a P2X2 / P2X3 heterodimer protein that is properly folded.

3. The isolated antibody or antigen binding fragment of claim 1, wherein the isolated antibody or antigen binding fragment binds to a P2X3 protein, a P2X2 protein, or a P2X2 / P2X3 heterodimer protein that is in a cell membrane.

4. The isolated antibody or antigen binding fragment of claim 1, wherein the isolated antibody or antigen binding fragment binds to a P2X3 protein, a P2X2 protein, or a P2X2 / P2X3 heterodimer protein that is in a cell membrane in an intact cell.

5. The isolated antibody or antigen binding fragment of claim 1, wherein the isolated antibody or antigen binding fragment inhibits the function of the P2X3 protein, the P2X2 protein, or the P2X2 / P2X3 heterodimer protein.

6. The isolated antibody or antigen binding fragment of claim 1, wherein the isolated antibody or antigen binding fragment inhibits the ion transport facilitated by the P2X3 protein, the P2X2 protein, or the P2X2 / P2X3 heterodimer.

7. The isolated antibody or antigen binding fragment any one of claims 1-6, wherein the isolated antibody or antigen binding fragment comprises a heavy chain CDR or an antigen binding fragment thereof described in Table 4.

8. The isolated antibody or antigen binding fragment of any one of claims 1-7, wherein the isolated antibody or antigen binding fragment comprises a light chain CDR or an antigen binding fragment thereof described in Table 4.

9. The isolated antibody or antigen binding fragment of any one of claims 1-8, wherein -71- IPTS / 200096106.1Attorney Docket No. ITL-013WO the isolated antibody or antigen binding fragment comprises one or more amino acid sequences of SEQ ID NOs: 1-146 and the amino acid sequences ofDND, WND,DNT, SNN, SND,DST,QNN, SSD, and NND, an antigen binding fragment thereof, or a human IgG variant thereof.

10. The isolated antibody or antigen binding fragment of any one of claims 1-9, wherein the antibody or antigen binding fragment comprises: (a) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 3, an HCDR2 amino acid sequence set forth in SEQ ID NO: 4, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 5, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 6, an LCDR2 amino acid sequence ofDND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 7; (b) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 15, an HCDR2 amino acid sequence set forth in SEQ ID NO: 16, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 17, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 18, an LCDR2 amino acid sequence of WND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 19; (c) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 27, an HCDR2 amino acid sequence set forth in SEQ ID NO: 28, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 29, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 30, an LCDR2 amino acid sequence of DNT, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 31; (d) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 40, an HCDR2 amino acid sequence set forth in SEQ ID NO: 41, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 42, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 43, an LCDR2 amino acid sequence of SNN, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 44; (e) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 53, an HCDR2 amino acid sequence set forth in SEQ ID NO: 41, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 54, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 55, an LCDR2 amino acid sequence of SND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 56; (f) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: -72- IPTS / 200096106.1Attorney Docket No. ITL-013WO 53, an HCDR2 amino acid sequence set forth in SEQ ID NO: 41, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 54, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 64, an LCDR2 amino acid sequence of SND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 65; (g) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 69, an HCDR2 amino acid sequence set forth in SEQ ID NO: 70, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 71, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 72, an LCDR2 amino acid sequence of DST, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 73; (h) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 83, an HCDR2 amino acid sequence set forth in SEQ ID NO: 84, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 85, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 86, an LCDR2 amino acid sequence of QNN, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 87; (i) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 95, an HCDR2 amino acid sequence set forth in SEQ ID NO: 96, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 97, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 98, an LCDR2 amino acid sequence of SND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 99; (j) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 106, an HCDR2 amino acid sequence set forth in SEQ ID NO: 107, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 108, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 109, an LCDR2 amino acid sequence of SND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 110; (k) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 95, an HCDR2 amino acid sequence set forth in SEQ ID NO: 96, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 108, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 98, an LCDR2 amino acid sequence of SSD, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 117; (l) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 106, an HCDR2 amino acid sequence set forth in SEQ ID NO: 107, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 108, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 121, an LCDR2 amino acid sequence of -73- IPTS / 200096106.1Attorney Docket No. ITL-013WO DNT, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 122; (m) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 106, an HCDR2 amino acid sequence set forth in SEQ ID NO: 107, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 108, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 126, an LCDR2 amino acid sequence of SND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 110; (n) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 95, an HCDR2 amino acid sequence set forth in SEQ ID NO: 96, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 130, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 98, an LCDR2 amino acid sequence of SND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 99; (o) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 95, an HCDR2 amino acid sequence set forth in SEQ ID NO: 134, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 130, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 135, an LCDR2 amino acid sequence of NND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 136; (p) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 106, an HCDR2 amino acid sequence set forth in SEQ ID NO: 107, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 130, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 126, an LCDR2 amino acid sequence of SND, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 142; (q) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 69, an HCDR2 amino acid sequence set forth in SEQ ID NO: 70, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 71, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 144, an LCDR2 amino acid sequence of DST, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 73; or (r) a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 145, an LCDR2 amino acid sequence ofSND, and an LCDR3 amino acid sequence set forth in SEQ ID NO:

146.

11. The isolated antibody or antigen binding fragment of any one of claims 1-9, wherein the antibody or antigen binding fragment comprises: (a) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 8, -74- IPTS / 200096106.1Attorney Docket No. ITL-013WO an HCDR2 amino acid sequence set forth in SEQ ID NO: 9, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 10, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 11, an LCDR2 amino acid sequence set forth in SEQ ID NO: 12, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 7; (b) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 20, an HCDR2 amino acid sequence set forth in SEQ ID NO: 21, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 22, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 23, an LCDR2 amino acid sequence set forth in SEQ ID NO: 24, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 19; (c) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 32, an HCDR2 amino acid sequence set forth in SEQ ID NO: 33, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 34, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 35, an LCDR2 amino acid sequence set forth in SEQ ID NO: 36, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 31; (d) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 45, an HCDR2 amino acid sequence set forth in SEQ ID NO: 46, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 47, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 48, an LCDR2 amino acid sequence set forth in SEQ ID NO: 49, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 44; (e) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 57, an HCDR2 amino acid sequence set forth in SEQ ID NO: 58, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 59, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 60, an LCDR2 amino acid sequence set forth in SEQ ID NO: 61, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 56; (f) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 57, an HCDR2 amino acid sequence set forth in SEQ ID NO: 58, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 59, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 66, an LCDR2 amino acid sequence set forth in SEQ ID NO: 61, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 65; -75- IPTS / 200096106.1Attorney Docket No. ITL-013WO (g) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 74, an HCDR2 amino acid sequence set forth in SEQ ID NO: 75, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 76, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 77, an LCDR2 amino acid sequence set forth in SEQ ID NO: 78, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 73; (h) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 74, an HCDR2 amino acid sequence set forth in SEQ ID NO: 80, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 76, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 77, an LCDR2 amino acid sequence set forth in SEQ ID NO: 78, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 73; (i) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 88, an HCDR2 amino acid sequence set forth in SEQ ID NO: 89, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 90, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 91, an LCDR2 amino acid sequence set forth in SEQ ID NO: 92, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 87; (j) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 amino acid sequence set forth in SEQ ID NO: 101, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 102, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 103, an LCDR2 amino acid sequence set forth in SEQ ID NO: 61, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 99; (k) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 amino acid sequence set forth in SEQ ID NO: 111, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 112, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 113, an LCDR2 amino acid sequence set forth in SEQ ID NO: 114, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 110; (l) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 amino acid sequence set forth in SEQ ID NO: 118, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 112, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 103, an LCDR2 amino acid sequence -76- IPTS / 200096106.1Attorney Docket No. ITL-013WO set forth in SEQ ID NO: 119, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 117; (m) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 amino acid sequence set forth in SEQ ID NO: 111, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 112, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 123, an LCDR2 amino acid sequence set forth in SEQ ID NO: 36, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 122; (n) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 amino acid sequence set forth in SEQ ID NO: 111, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 112, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 127, an LCDR2 amino acid sequence set forth in SEQ ID NO: 61, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 110; (o) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 amino acid sequence set forth in SEQ ID NO: 101, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 131, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 103, an LCDR2 amino acid sequence set forth in SEQ ID NO: 61, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 99; (p) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 amino acid sequence set forth in SEQ ID NO: 137, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 131, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 138, an LCDR2 amino acid sequence set forth in SEQ ID NO: 139, and an LCDR3 amino acid sequence set forth in SEQ ID NO: 136; or (q) a VH comprising an HCDR1 amino acid sequence set forth in SEQ ID NO: 100, an HCDR2 amino acid sequence set forth in SEQ ID NO: 111, and an HCDR3 amino acid sequence set forth in SEQ ID NO: 131, and a VL comprising an LCDR1 amino acid sequence set forth in SEQ ID NO: 127, an LCDR2 amino acid sequence set forth in SEQ ID NO: 61, and an LCDR3 amino acid sequence set forth in SEQ ID NO:

142.

12. The isolated antibody or antigen binding fragment of any one of claims 1-11, wherein -77- IPTS / 200096106.1Attorney Docket No. ITL-013WO the isolated antibody or antigen-binding fragment comprises a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to an amino acid sequence as set forth in SEQ ID NO: 1, 13, 25, 37, 38, 51, 62, 67, 79, 81, 93, 104, 115, 124, 128, 132, or 140.

13. The isolated antibody or antigen binding fragment of any one of claims 1-12, wherein the isolated antibody or antigen-binding fragment comprises a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to an amino acid sequence as set forth in SEQ ID NO: 2, 14, 26, 39, 50, 52, 63, 68, 82, 94, 105, 116, 120, 125, 129, 133, 141, or 143.

14. The isolated antibody or antigen binding fragment of any one of claims 1-13, wherein the isolated antibody or antigen-binding fragment comprises (i) a VH comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to an amino acid sequence as set forth in SEQ ID NO: 1, 13, 25, 37, 38, 51, 62, 67, 79, 81, 93, 104, 115, 124, 128, 132, or 140; and (ii) a VL comprising an amino acid sequence at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5% or 100% identical to an amino acid sequence as set forth in SEQ ID NO: 2, 14, 26, 39, 50, 52, 63, 68, 82, 94, 105, 116, 120, 125, 129, 133, 141, or 143.

15. The isolated antibody or antigen-binding fragment of any one of claims 1-14, wherein the isolated antibody or antigen-binding fragment is selected from the group consisting of an antibody, a single chain variable fragment (scFv), a Fab fragment, a Fab′ fragment, a single- chain Fab fragment (scFab), and a F(ab′)2 fragment.

16. The isolated antibody or antigen-binding fragment of any one of claims 1-15, wherein the antibody is an IgG1, an IgG2, an IgG3, an IgG4, an IgA, an IgD, an IgE, or an IgM antibody.

17. An isolated antibody or antigen-binding fragment thereof that competes with the -78- IPTS / 200096106.1Attorney Docket No. ITL-013WO isolated antibody or antigen-binding fragment of any one of claims 1-16 for binding to the P2X3 protein, the P2X2 protein, or the P2X2 / P2X3 heterodimer.

18. An isolated antibody or antigen-binding fragment comprising a means for binding to a P2X3 protein, a P2X2 protein, or a P2X2 / P2X3 heterodimer.

19. A pharmaceutical composition comprising the isolated antibody or antigen binding fragment of any one of claims 1-18.

20. The pharmaceutical composition of claim 19, wherein the composition is an injectable pharmaceutical composition.

21. The pharmaceutical compositions of claims 19 or 20, wherein the composition is sterile.

22. The pharmaceutical compositions of claims 19 or 20, wherein the composition is pyrogen free.

23. The pharmaceutical compositions of any one of claims 19-22, wherein the composition is free of antibodies that do not bind to P2X3.

24. A method of treating, inhibiting or ameliorating a P2X3, a P2X2, or a P2X2 / P2X3 associated pathology comprising administering an isolated antibody or antigen binding fragment of any one of claims 1-18 or a pharmaceutical composition of any one of claims 19- 23.

25. The method of claim 24, wherein the P2X3, P2X2, or a P2X2 / P2X3 associated pathology is pain.

26. The method of claim 25, wherein the method alleviates the symptoms of a P2X3, a P2X2, or a P2X2 / P2X3 associated pain.

27. A method of inhibiting a P2X3, a P2X2, or a P2X2 / P2X3 activity comprising contacting a P2X3, a P2X2, or a P2X2 / P2X3 protein with an isolated antibody or antigen -79- IPTS / 200096106.1Attorney Docket No. ITL-013WO binding fragment of any one of claims 1-18 or a pharmaceutical composition of any one of claims 19-23.

28. The method of claim 27, wherein the isolated antibody or antigen binding fragment is a human IgG antibody.

29. A method of detecting the presence or absence of a P2X3 in a sample comprising contacting a sample with an isolated antibody or antigen binding fragment of any one of claims 1-18 and detecting the binding to a P2X3 antigen by the isolated antibody or antigen binding fragment, wherein the detection of the binding indicates the presence of the P2X3 antigen; or the absence of the detection of the binding to the P2X3 antigen indicates the absence of the P2X3 antigen.

30. A method of identifying an antibody that binds to an epitope on a P2X3 protein, a P2X2 protein, or a P2X2 / P2X3 heterodimer protein, the method comprising contacting a test antibody with the epitope on the P2X3 protein, the P2X2 protein, or the P2X2 / P2X3 heterodimer protein and determining whether the test antibody binds to the epitope, wherein the determining comprises determining whether an antibody of any one of claims 1-18 competitively inhibits the binding of the test antibody to the epitope.

31. The method of claim 30, wherein the determining comprises mutating one or more residues of epitope and determining binding of the test epitope, wherein if the mutation reduces binding of the test antibody, the test antibody is deemed to bind to that epitope.

32. A method of inducing an immune response against a P2X3 antigen, a P2X2 antigen, or a P2X2 / P2X3 heterodimer antigen comprising administering the P2X3 antigen, the P2X2 antigen, or the P2X2 / P2X3 heterodimer antigen to a subject under conditions sufficient to induce an immune response.

33. The method of claim 32, wherein the method comprises administering a lipoparticle comprising the P2X3 antigen, the P2X2 antigen, or the P2X2 / P2X3 heterodimer antigen to the subject. -80- IPTS / 200096106.1Attorney Docket No. ITL-013WO 34. The method of claims 32 or 33, wherein the subject is a chicken. -81- IPTS / 200096106.1

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