Nanobodies capable of cross-binding to several different elapid three-finger toxins

Abstract

The invention relates to a monoclonal binding agent comprising complementary determining regions CDR1, CDR2, and CDR3 of a single domain antibody (sdAb), the monoclonal binding agent being able to bind and / or block and / or neutralise Elapidae three-finger toxins (3FTx) of multiple snake species, wherein the monoclonal binding agent is selected from an antibody, an antibody format, an antibody fragment or an antibody analogue.

Description

[0001]NANOBODIES CAPABLE OF CROSS-BINDING TO SEVERAL DIFFERENT ELAPID THREE-FINGER TOXINS FIELD OF THE INVENTION The present invention relates to a monoclonal binding agent comprising determining regions CDR1, CDR2, and CDR3 of a single domain antibody (sdAb), said monoclonal binding agent being able to bind and / or block and / or neutralise Elapidae three-finger toxins (3FTx) of multiple snake species, wherein the monoclonal binding agent is selected from an antibody, antibody fragment or antibody analogue. The invention also relates to a single-domain antibody (sdAb) comprising complementary determining regions CDR1, CDR2, and CDR3, said sdAb being able to bind and / or block and / or neutralize Elapidae three-finger toxins (3FTx) of multiple snake species. BACKGROUND OF THE INVENTION Despite not being considered in our daily lives in most of Europe, snakebite envenoming represents a significant public health issue worldwide. In 2017, the World Health Organization (WHO) reinstated snakebite envenoming as a neglected tropical disease. This category encompasses a group of infections or conditions that primarily affect the world's poorest populations and have received little attention in terms of research and development. Snakebite envenoming imposes a considerable burden of morbidity and mortality, with conservative estimates indicating tens of thousands of deaths annually. In addition to the lives lost, survivors often face permanent disabilities and socioeconomic hardships, leaving approximately 400,000 victims with permanent sequelae such as amputation or disfigurements. Beyond its immediate health consequences, snakebite envenoming exerts a far-reaching influence on communities and societies, especially in rural and developing regions where snakebites are more prevalent and access to timely medical care is challenging. Snakebite envenoming represents a significant global health problem in terms of mortality and the long-term socioeconomic impact on affected individuals and communities. Understanding the complex nature of snakebite envenoming requires a comprehensive exploration of the venom composition and the toxins responsible for the deleterious effects. Snake venoms are a mixture of salts, small organic molecules, peptides, and proteins commonly known as toxins. These toxins constitute a diverse and complex arsenal that varies significantly among the approximately 700 species of venomous snakes, which are categorized into four main families: Viperidae, Elapidae, Atractaspididae, and Colubridae. The Viperidae (vipers, adders, and pit vipers) and Elapidae (cobras, mambas, kraits, Australasian venomous snakes, and sea snakes) are the most medically relevant families, responsible for the majority of snakebite envenoming worldwide. The clinical manifestations of snakebite envenoming depend highly on the specific snake species involved, which is directly related to the venom composition. Venom can induce various toxic effects, including neurotoxicity, hemotoxicity, cytotoxicity, and myotoxicity. The composition of venom exhibits considerable variation not only between different snake species but also within the same species, influenced by factors such as age, sex, diet, and geographical location. A widely accepted classification includes four major categories: Phospholipases A2 (PLA2), snake venom metalloproteases (SVMPs), snake venom serine proteases (SVSPs), and three- finger toxins (3FTxs). Although 3FTxs can be found in the venoms of all snake families, they are particularly abundant in Elapid venoms. Remarkably, they constitute a significant proportion, ranging from 64% to 95%, of all toxins present in the venoms of renowned snakes such as shield-nosed cobras (Aspidelaps spp.), green mambas (Dendroaspis angusticeps), the king cobra (Ophiophagus hannah), and the entire genus of true cobras (Naja spp.). Three-finger toxins (3FTxs) are a medically relevant group of non-enzymatic proteins found in snake venoms, known for their diverse range of biological activities and unique structural characteristics. These toxins derive their name from their distinctive three-finger fold structure, which features a protein scaffold consisting of three β-stranded loops that resemble fingers, converging at a hydrophobic core held together by four conserved disulfide bridges. This arrangement results in a flat, leaf-like shape with a slight concavity. The broad spectrum of biological activities exhibited by 3FTxs highlights their functional versatility. These toxins exert various pharmacological actions, including cytotoxicity, coagulotoxicity, cardiotoxicity, neurotoxicity, and acetylcholinesterase inhibition. The diverse toxic effects exerted by 3FTxs arise from differences in their primary sequences, unique pharmacophores, and variations in the length, loops, and flexibility. Additional disulfide bridges and extensions of the N- and C-termini further contribute to the distinct functions observed among different 3FTxs. A subgroup of the 3FTxs family is known as α-neurotoxins. These toxins have a crucial function in snakebite envenoming, especially when bitten by an elapid, by exerting their action postsynaptically at neuromuscular junctions. They achieve this by binding with high affinity to the cholinergic receptor at the motor end plate in muscle fibers, effectively hindering the binding of acetylcholine. Consequently, this provokes flaccid paralysis, which can lead to respiratory failure and asphyxiation due to the immobilization of the respiratory muscles. α-neurotoxins can be further categorized based on their structural characteristics. One structural classification widely accepted by the toxinology scientific community divides α- neurotoxins into short-chain α-neurotoxins (SC), long-chain α-neurotoxins (LC), non- conventional α-neurotoxins (NC-α-neurotoxins), and atypical α-neurotoxins, each with variances in primary and tertiary structure. SC-α-neurotoxins typically consist of approximately 60-62 residues and contain four conserved disulfide bridges. In comparison, LC-α-neurotoxins are larger, ranging from 66 to 75 residues, and possess an additional disulfide bond at the tip of the second loop. They also display a shorter first loop and a longer C-terminal tail. NC-α-neurotoxins are approximately 62-68 residues long and have a fifth disulfide bridge in the first loop. Atypical α-neurotoxins exhibit considerable variation in length, ranging from 57 to 87 residues, and may contain an additional disulfide bond in either the first or second loop. It is worth noting that some α-neurotoxins can exist in a dimeric form. These dimeric α- neurotoxins can either be covalently-bound dimers with one or more disulfide bridges or non- covalently bound dimers held together by hydrophobic interactions or hydrogen bonds. The dimerization of α-neurotoxins leads to the diversification of target selectivity by enabling novel structural conformations that allow interactions with new receptor subtypes not targeted by their monomeric constituents. The primary target of all α-neurotoxins is the nicotinic acetylcholine receptor (nAChR). This receptor plays a critical role in transmitting signals between nerve cells and muscle cells, specifically at the neuromuscular junction. By binding to the orthosteric ligand-binding sites of nAChR, α-neurotoxins disrupt the normal function of this receptor by preventing the neurotransmitter acetylcholine (ACh) from binding, which leads to the inhibition of muscle contraction. This interference with acetylcholine transmission leads to muscle paralysis, ultimately causing respiratory failure and potentially resulting in asphyxiation. These toxins possess a high affinity and selectivity for the nAChR, allowing them to specifically target and block neuromuscular transmission. A common binding core of amino acids present in the toxin’s structure, including positively charged and aromatic residues, facilitates the recognition of the nAChR by α-neurotoxins. One notable feature of α-neurotoxins is the presence of a highly conserved arginine residue located at the tip of the second loop. This arginine residue plays a critical role in toxin binding and interaction with the nAChR. It mimics the shape and physicochemical properties of acetylcholine, the natural ligand of the receptor, by occupying the orthosteric ligand-binding site on the nAChR. By binding to this site, α-neurotoxins prevent acetylcholine from effectively binding and opening the receptor channel. Traditional antivenom requires the immunisation of large animals and the subsequent purification of antibodies from their plasma, however there are limitations. One of the major challenges lies in generating antibodies that efficiently neutralize all medically relevant snake venom toxins. The efficacy of the antivenoms heavily relies on the immunogenicity and the abundance of the toxin in the venoms used for immunizations. Certain toxins, such as the α- neurotoxins and other 3FTxs, are not very immunogenic, or they are not present in a sufficient concentration in the venom to effectively trigger an immune response in the immunized animal. Consequently, traditional antivenoms often contain a limited proportion of antibodies capable of neutralizing venom effects. This is particularly problematic since toxins with low immunogenicity can be medically relevant, and exert toxic effects even at low doses. Traditional antivenoms, which are polyclonal mixtures, consist of a vast but unknown number of unique antibodies. While they primarily target toxins they were raised against, they also recognize numerous other proteins from foreign pathogens encountered by the antivenom production animal throughout its life. Among these antibodies, only approximately 10 to 40% specifically target the toxins in the venom, leaving the majority to focus on non-snake toxin molecules or proteins. Consequently, higher dosages of antivenom are often necessary to achieve venom neutralization. Moreover, the specific antibody clones present in a given antivenom product can vary between batches, as different antivenom batches are typically sourced from distinct production animals. This inherent variability adds complexity and challenges to antivenom efficacy and consistency. Further, traditional antivenoms are typically not registered without a diagnosis due to the risk of severe adverse reactions. The immunogenicity of antivenoms can lead to serum sickness, an immune complex-mediated hypersensitivity reaction. Species-specificity is yet another limitation of traditional antivenoms, which arises from the fact that they are typically developed using venom from a specific snake species. While these antivenoms are effective against the toxins produced by that particular snake species, they may not be effective against the toxins from other snake species. Another drawback of traditional antivenom production is the cost associated with manufacturing and distributing antivenom on a large scale. It is a complex and labor- intensive process to produce antivenom with various stages such as venom collection, animal immunization, antibody purification, and quality control. These processes require specialized facilities, equipment, and skilled personnel, all of which contribute to the overall cost of antivenom production. The high cost of manufacturing antivenom can have profound implications for regions with limited healthcare resources, particularly in developing countries where snakebite envenomation is a significant health problem. The expense associated with antivenom production can make it unaffordable or economically unsustainable for healthcare systems and individuals in these regions. Consequently, there is a need for improved antivenoms to address the challenges associated with traditional antivenom production. OBJECT OF THE INVENTION It is an object of embodiments of the invention to provide an improved recombinant antivenom with broad binding and / or broadly neutralising ability. SUMMARY OF THE INVENTION It has been found by the present inventor(s) that using consensus toxins and phage display technology, cross-reactive monoclonal binding agents comprising single-domain antibodies (sdAbs) may be created and selected that can broadly neutralize snake venom toxins. The discovered sdAbs exhibit high affinity towards native toxins from different snake species, with some showing sub-picomolar affinity and the ability to neutralize toxins from diverse elapid species. So, in a first aspect the present invention relates to a monoclonal binding agent comprising complementary determining regions CDR1, CDR2, and CDR3 of a single domain antibody (sdAb), said monoclonal binding agent being able to bind and / or block and / or neutralise Elapidae three-finger toxins (3FTx) of multiple snake species, wherein the monoclonal binding agent is selected from an antibody, antibody fragment or antibody analogue. In a second aspect, the invention relates to a single-domain antibody (sdAb) comprising complementary determining regions CDR1, CDR2, and CDR3, said sdAb being able to bind and / or block and / or neutralize Elapidae three-finger toxins (3FTx) of multiple snake species. In a third aspect, the invention relates to a pharmaceutical composition comprising the monoclonal binding agent according to the first aspect or one or more sdAb according to the second aspect, wherein the composition further comprises a pharmaceutically acceptable carrier and / or vehicle and / or diluent and / or excipient. In a fourth aspect, the invention relates to a method for treatment of snake envenomation, the method comprising administering an effective amount of the monoclonal binding agent according to the first aspect or one or more sdAb according to the second aspect or the pharmaceutical composition according to the third aspect. In a fifth aspect, the invention relates to the monoclonal binding agent according to the first aspect, one or more sdAb according to the second aspect or the pharmaceutical composition according to the third aspect for use as a medicament, preferably for use in the treatment or prevention of snake envenomation. In a sixth aspect, the invention relates to a method of producing a monoclonal binding agent according to the first aspect or one or more sdAb according to the second aspect, the method comprising the step of: screening an sdAb-displaying phage library against a polypeptide comprising or consisting of a consensus sequence of at least 2 distinct three-finger toxins (3FTxs) from multiple Elapidae snake species; and isolating sdAb species from the library that bind the polypeptide and selecting from these isolated sdAb species those that verifiably bind to Elapidae three-finger toxins (3FTx) of multiple snake species, and if necessary, grafting CDR sequences from the selected sdAb species to obtain a monoclonal binding agent as defined the first aspect. In a seventh aspect, the invention relates to the monoclonal binding agent according to the first aspect or one or more sdAbs according to the second aspect for use in a method of diagnosis of snake envenomation in a subject affected thereof. LEGENDS TO THE FIGURE Figure 1 shows BLI binding curves from sdAbs from TPL1158. The measured binding curves of the sdAbs from the TPL1158 selection against three different LC-α-neurotoxins including their fitted curves. Figure 2 shows BLI binding curves from sdAbs from TPL1163. The measured binding curves of the sdAbs from the TPL1163 selection against three different short α-neurotoxins including their fitted curves. No binding was observed for TPL1163_01_C11, 01_G05, and 02_A01 to Dp4. Figure 3 shows results from a receptor binding inhibition screening against five long-chain ɑ- neurotoxins. The ability of selected sdAbs to prevent long-chain α-neurotoxins from binding to the human acetylcholine receptor was assessed with a DELFIA. An isotype sdAb that was specific to cytotoxins was included as a negative control. The vertical dotted line indicates a 1:1 molar ratio of sdAb:toxin. Figure 4 shows the in vitro neutralization capabilities of sdAbs against various α-neurotoxins. The sdAbs were preincubated with different molar ratios of sdAb:toxin, and the resulting normalized peak current is shown. Toxins were used at concentrations ranging between IC10and IC90, as indicated by the peak current obtained when no sdAb was present. Figure 5 shows Kaplan-Meier survival curves for mice challenged with α-cobratoxin and sdAbs. 3 LD50s of α-cobratoxin were preincubated with either PBS or one of the sdAbs and injected in mice using the i.v. route. n = 3. * Indicates a significant difference to PBS control (P < 0.05) in a Mantel-Cox log-rank test. Figure 6 shows predicted hydrogen bond interactions of sdAb TPL1158_01_C09 (C09) with ɑ- cobratoxin (ɑ-cbtx), ɑ-neurotoxin (ɑ-ntx, from D. polylepis), ɑ-consensus toxin (LCC), and ɑ- bungarotoxin (ɑ-btx). A) Interactions of the X-ray complex structure of C09 with ɑ-cbtx mapped onto the epitope (top) and the paratope (bottom). The close-up shows the predicted hydrogen bond network obtained from molecular dynamic simulations mapped onto the respective epitope (top) and the paratope (bottom). Amino acid residues of C09: D27, W99, T100A, Y100, S100B, D100G; amino acid residues of ɑ-cbtx: P7, D27, R33, K35, R36, V37. B) Hydrogen bond network obtained from molecular dynamic simulations mapped onto the respective epitope (top) and the paratope (bottom) for each of the sdAb:toxin complexes with the toxins as indicated. DETAILED DISCLOSURE OF THE INVENTION Abbreviations 3FTX Three-finger toxins BLI Biolayer interferometry CDR Complementarity-determining region DEFLIA Dissociation-enhanced lanthanide fluorescence immunoassay Fab Antigen-binding fragment IgG Immunoglobulin G LC Long-chain LCC Long-chain consensus toxin nAChR Nicotinic acetylcholine receptor NC Non-conventional SC Short-chain SCC Short-chain consensus toxin scFv Single-chain variable fragment SVMP Snake venom metalloproteases SVSP Snake venom serine proteases VHH Variable heavy-chain antibodies Definitions An “antibody”, which is also termed an “immunoglobulin”, is a protein, which in humans consists of pairwise identical light chains and heavy chains, where the heavy and light chains each comprise a variable domain and a constant region, wherein the variable domains are responsible for the antibody’s specific binding to an antigen. Generally, antibodies are grouped into the immunoglobulin isotypes IgA, IgD, IgE, IgG and IgM, which each play different roles as antigen-recognizing agents in the immune system. The specificity for antigen binding of an antibody is determined by variable regions in the variable domains, and in particular by the complementarity determining-regions (CDRs) in the variable domains. Generally, antibodies are molecules, which in principle or in practice can be expressed in its natural conformation in an animal, meaning that the expressed antibody includes all structural elements found in a naturally occurring immunoglobulin. An “antibody variant” is a protein derived from an antibody, which has the same binding specificity as an antibody, but which would not be a natural expression product in a mammal. As such, the term refers to various fragments of antibodies as well as artificial antibody analogue formats. Also, the term denotes antibody formats that are found in nature, but which are uncommon among mammals, such as heavy-chain antibodies and IgY found in birds and reptiles, but where CDRs from mammalian antibodies or combinatorically produced antibodies have been engineered into an antibody format from which it is not originally derived. A “heavy chain-only antibody” is an antibody format naturally found in camelids (such as camels, dromedaries, llamas, and alpacas) or in cartilaginous fish (such a sharks, skates, rays, sawfish etc.) and consists of only two heavy chains lacking the two light chains. The term ‘monoclonal binding agent’ refers to an antibody, antibody fragment or antibody analogue comprising complementary determining regions CDR1, CDR2, and CDR3 of a single domain antibody (sdAb). The term ‘single domain antibody’ which may also be termed a “nanobody”, is an antibody fragment in the form of a single monomeric variable antibody domain that is able to bind selectively to a specific antigen. Conventionally, an sdAb is a fragment of a heavy chain-only antibody comprising the antibody’s VH domain. SdAbs bind antigens using only three complementarity-determining regions (CDR1, CDR2 and CDR3) rather than the six present in conventional VH:VL antibodies. However, an sdAb can also in some cases be derived from a common antibody such as IgG, but this approach requires abrogation of the natural dimerisation of VH and VL domains by amino acid substitution, meaning that antigen affinity is often compromised. Typically, sdAbs are relatively short in comparison to full-size IgGs, such as 100-200 amino acid residues. Further, sdAbs are antibodies whose CDRs are part of a single domain polypeptide. Examples include, but are not limited to, heavy chain antibodies, antibodies naturally devoid of light chains, single domain antibodies derived from conventional 4-chain antibodies, engineered antibodies and single domain scaffolds other than those derived from antibodies. SdAbs may be derived from any species including, but not limited to mouse, human, shark, camel, llama, goat, rabbit, and / or bovine. In some embodiments, an sdAb as used herein is the variable domain derived from a naturally occurring heavy chain antibody devoid of light chains. For clarity reasons, this variable domain derived from a heavy chain only antibody is known as a VHH domain to distinguish it from the conventional VH of four chain immunoglobulins. In here, the term sdAb is interchangeable with an VHH antibody. When the sdAb is part of a fusion protein / fusion construct, the term sdAb may be interchangeable with VHH domain. Such a VHH domain can be derived from antibodies raised in animals able to produce heavy chain only antibodies. By example are Camelidae species, e.g., camel, llama, dromedary, alpaca and guanaco. Other species besides Camelidae may produce heavy chain only antibodies and such VHHs are within the scope of the disclosure. Therefore, in any construct described herein, wherein an sdAb is part of a larger construct, the term sdAb or nanobody is exchangeable with the term VHH. A binding region of an sdAb herein is meant to include one or more or all the three complementarity-determining regions (CDR1, CDR2 and CDR3). A "complementarity-determining region" or "CDR", is a variable part of an antibody, including sdAbs and thus crucial to the diversity. Not all residues in the CDRs might be responsible for epitope binding. Ex. cysteines in CDR1 and CDR3 of sdAbs are determining for the structure (Pellis et al., 2012) In some embodiments, an sdAb comprises three CDRs and four framework regions (FRs), arranged in the following order: FR1, CDR1, FR2, CDR2, FR3, CDR3 and FR4. In some embodiments, an sdAb may be truncated at the N-terminus or C-terminus such that it comprises only a partial FR1 and / or FR4, or lacks one or both of those FRs, so long as the VHH / sdAb substantially maintains the desired antigen binding and specificity. For example, SCC TPL1163_01_H08 (154 aa) comprises three CDRs and four framework regions (FRs): QVQLQESGGGSVQAGGSLRLSCTASDGSLSTYTVGWFRQVSEVGRDLVAQSGSAGSDDEDTHV AGSVAGRFTISRDNTENTVYLQMNNLTPEDTAVYYCAAAPGDHYTNWGQGTQVTVSSAAADYK DHDGDYKDHDIDYKDDDDKGAAHHHHHH (SEQ ID NO: 3), wherein the bold letters refer to FR1, the first instance of Italics and underlined letters refer to CDR1, the bold and italics letters refer to FR2, the italics letters refer to CDR2, the bold and underlined letters refer to FR3, the second instance of Italics and underlined letters refer to CDR3 and the bold, Italics and underlined letters refer to FR4. Similarly, TPL1163_01_C11 (157 aa): QVQLQESGGGVVQAGGSLRLSCAVSGVSESIFANYVVGWFRQQDSGTGRDLVAQSSSDDEYNH VSGSVKGRFTISRDNAKNTVSLQMDNVKPEDTATYICAAALGPGDNYIYWGQGTQVTVSSAAAD YKDHDGDYKDHDIDYKDDDDKGAAHHHHHH (SEQ ID NO: 4), wherein the bold letters refer to FR1, the first instance of Italics and underlined letters refer to CDR1, the bold and italics letters refer to FR2, the italics letters refer to CDR2, the bold and underlined letters refer to FR3, the second instance of Italics and underlined letters refer to CDR3 and the bold, Italics and underlined letters refer to FR4. TPL1163_01_G05 (157 aa) comprises the following CDRs and FRs: QVQLQESGGGLVRPGGSLRLSCAVSGVSESIFANYVVGWFRQQDSGTGRDLVAQSSSDDEYNH VSGSVKGRFTISRDNAKNTVSLQMDNLKPEDTAIYICAAAIGPGDNYIYWGQGTQVTVSSAAAD YKDHDGDYKDHDIDYKDDDDKGAAHHHHHH (SEQ ID NO: 5), wherein the bold letters refer to FR1, the first instance of Italics and underlined letters refer to CDR1, the bold and italics letters refer to FR2, the italics letters refer to CDR2, the bold and underlined letters refer to FR3, the second instance of Italics and underlined letters refer to CDR3 and the bold, Italics and underlined letters refer to FR4. TPL1163_02_A01 (157 aa) comprises the following CDRs and FRs: QVQLQESGGGLVRPGGSLRLSCAVSGVSESIFAKYVVGWFRQQDSGTGRDLVAQSSSDDEYNHV SGSVKGRFTISRDNAKNTVSLQMDNVKPEDTATYICAAAPGPGDNYIYWGQGTQVTVSSAAADY KDHDGDYKDHDIDYKDDDDKGAAHHHHHH (SEQ ID NO: 6), wherein the bold letters refer to FR1, the first instance of Italics and underlined letters refer to CDR1, the bold and italics letters refer to FR2, the italics letters refer to CDR2, the bold and underlined letters refer to FR3, the second instance of Italics and underlined letters refer to CDR3 and the bold, Italics and underlined letters refer to FR4. TPL1158_01_A11 (160 aa) comprises the following CDRs and FRs: QVQLQESGGGLVQTGGSLTLSCAASGFTFDDWAIAWFRQAPGKEREGVSVLPISDPPATAYGHFV KGRFSISTNNARNTVYLQMNNLKPEDTAVYYCAASRFWGSNWKDPPEYDYWGQGTQVTVSSAA ADYKDHDGDYKDHDIDYKDDDDKGAAHHHHHH (SEQ ID NO: 7), wherein the bold letters refer to FR1, the first instance of Italics and underlined letters refer to CDR1, the bold and italics letters refer to FR2, the italics letters refer to CDR2, the bold and underlined letters refer to FR3, the second instance of Italics and underlined letters refer to CDR3 and the bold, Italics and underlined letters refer to FR4. TPL1158_01_B05 (161 aa) comprises the following CDRs and FRs: QVQLQESGGGLAQPGGSLSLSCATTRDVGSIHAMAWYRQAPGKQRELVASVTMVGGETPTYAES IKGRFTISKDNDKNAISLQMSSLKPEDTAVYYCKADSYCSDSACYENPVFDYWGQGTQVTVSSAA ADYKDHDGDYKDHDIDYKDDDDKGAAHHHHHH (SEQ ID NO: 8), wherein the bold letters refer to FR1, the first instance of Italics and underlined letters refer to CDR1, the bold and italics letters refer to FR2, the italics letters refer to CDR2, the bold and underlined letters refer to FR3, the second instance of Italics and underlined letters refer to CDR3 and the bold, Italics and underlined letters refer to FR4. TPL1158_01_C04 (157 aa) comprises the following CDRs and FRs: QVQLQESGGGLVQPGGSLRLSCAASGDIAGLNNMGWYRQAPGKQRELVAAQARGGNTNYTDSV KGRFTISRDNAENTVYLQMNSLKSEDTAVYYCYAAVGNWYESGYYVDDYWGQGTQVTVSSAAA DYKDHDGDYKDHDIDYKDDDDKGAAHHHHHH (SEQ ID NO: 9), wherein the bold letters refer to FR1, the first instance of Italics and underlined letters refer to CDR1, the bold and italics letters refer to FR2, the italics letters refer to CDR2, the bold and underlined letters refer to FR3, the second instance of Italics and underlined letters refer to CDR3 and the bold, Italics and underlined letters refer to FR4. TPL1158_01_C09 (157 aa) comprises the following CDRs and FRs: QVQLQESGGGLVQPGGSLRLSCAASGDIGGLKQMGWYRQAPGHQRELVAVKRNENEANYTESV KGRFTISRDNARKMVYLQMNSLKPEDTAVYYCNAVVGNWYTSGYYEDTYWGQGTQVTVSSAAA DYKDHDGDYKDHDIDYKDDDDKGAAHHHHHH (SEQ ID NO: 10), wherein the bold letters refer to FR1, the first instance of Italics and underlined letters refer to CDR1, the bold and italics letters refer to FR2, the italics letters refer to CDR2, the bold and underlined letters refer to FR3, the second instance of Italics and underlined letters refer to CDR3 and the bold, Italics and underlined letters refer to FR4. TPL1158_02_C06 (159 aa) comprises the following CDRs and FRs: QVQLQESGGGLVQPGGSLRLSCAASGDIVSLNVMGWYRQAPGKQRELVAIMKKDTSTTYADSVK GRFTISRDNANHTSSLQMNSLEPEDTAVYYCNAAGVVYQQGVYMDYTKDYWGKGTQVTVSSAAA DYKDHDGDYKDHDIDYKDDDDKGAAHHHHHH (SEQ ID NO: 11), wherein the bold letters refer to FR1, the first instance of Italics and underlined letters refer to CDR1, the bold and italics letters refer to FR2, the italics letters refer to CDR2, the bold and underlined letters refer to FR3, the second instance of Italics and underlined letters refer to CDR3 and the bold, Italics and underlined letters refer to FR4. As previously described, the main purpose of CDR regions is to define the regions having specificity to an epitope. However, not all residues in the CDRs might be responsible for epitope binding but might merely determine structural elements (Wilton E. et al 2018 ref 6). In addition, the FRs might not exclusively responsible for the structure as residues of the FRs adjacent to CDRs can influence binding. Different methods can be applied for determination of the position of the different frameworks and CDR regions of an sdAb. One method is the "Kabat numbering scheme" or "Kabat", first described by American scientist Elvis Kabat. Here amino acid residues of an immunoglobulin single variable domain can be numbered according to the general numbering of VH domains given by Kabat et al. and applied to VHH domains from camelids as described in the by Riechmann and Muyldemans (Riechmann and Muyldemans, 1999). In CDR determination according to Kabat, for example, FR1 of TPL1163_01_H08 comprises the amino acids residues at position 1-25, CDR1 of TPL1163_01_H08 comprises the amino acids residues at position 23-33, FR2 of TPL1163_01_H08 comprises the amino acid position 34-50, CDR2 of TPL1163_01_H08 comprises the amino acid residues of position 51-61, FR3 of TPL1163_01_H08 comprises the amino acids residues at position 62-99, CDR3 of TPL1163_01_H08 comprises the amino acid residues at position 100-109, and FR4 of TPL1163_01_H08 comprises the amino acid residues at position 110-120. It should be noted that - as is well known in the art for VH domains and for VHH domains - the total number of amino acid residues in each of the CDRs may vary and may not correspond to the total number of amino acid residues indicated by the Kabat numbering. That is, one or more positions according to the Kabat numbering may not be occupied in the actual sequence, or the actual sequence may contain more amino acid residues than the number allowed for by the Kabat numbering). This means that, generally, the numbering according to Kabat may or may not correspond to the actual numbering of the amino acid residues in the actual sequence. The total number of amino acid residues in a VH domain and a VHH domain may typically be in the range of from 110 to 200, often between 140 and 160. It should however be noted that smaller and longer sequences may also be suitable for the purposes described herein. Another method for determining CDR regions in VHH is by Chothia numbering scheme. Here amino acid residues of an immunoglobulin single variable domain can be numbered using conserved amino acids, which always have the same position (Dondelinger M et al., 2018). A further method for determining CDR regions in VHH is by IMGT. Here amino acid residues of an immunoglobulin single variable domain can be numbered using conserved amino acids, which always have the same position. For instance, Cysteine 23, Tryptophane 41, Leucine 89, Cysteine 104. FR1 of a VHH comprises the amino acids residues at position 1-26, CDR1 of a VHH comprises the amino acids residues at position 27-38, FR2 of a VHH comprises the amino acid position 39-55, CDR2 of a VHH comprises the amino acid residues of position 56- 65, FR3 of a VHH comprises the amino acids residues at position 66-104, CDR3 of a VHH comprises the amino acid residues at position 105-117, and FR4 of a VHH comprises the amino acid residues at position 118 and the rest of the sequence. The maximum length of CDR is as defined above. For shorter CDRs, gaps are created (Lefranc et al., 2002). Alternatively, the CDR regions in an sdAb can be determined by using the AbM numbering as described in Kontermann and Dubel (Eds. 2010, Antibody Engineering, vol 2, Springer Verlag Heidelberg Berlin, Martin, Chapter 3, pp. 33-51). According to this method, FR1 comprises the amino acid residues at positions 1-25, CDR1 comprises the amino acid residues at positions 26-35, FR2 comprises the amino acids at positions 36-49, CDR2 comprises the amino acid residues at positions 50-58, FR3 comprises the amino acid residues at positions 59-94, CDR3 comprises the amino acid residues at positions 95-102, and FR4 comprises the amino acid residues at positions 103-113. A further method for determining the CDR regions in an sdAb is by using the Aho numbering scheme (Mitchelle & Colwell, 2017 and Honegger & Pluckthun et al., 2001). Another alternative for determining CDR regions in VHH is using sdAb-DB described by Emily Wilton in 2018. The method is built on a set of sequence-based rules for identifying CDRs in light and heavy chains of conventional antibodies by Pantazes and Maranas (Wilton E et al 2018 SyntheticBioloogy) and adopted to sdAbs. In sdAb-DB, CDR1 starts 4 residues after the first cysteine, with a length of 6-15 residues followed by a W. CDR2 starts 10-20 residues after end of CDR1 and following sequence [I / L / V / M]-[G / A / S]. The length of CDR2 is 8-15 residues and is followed by the sequence [Y / F / I / L / T / N / S / V / H]-X-X-X-[A / I / L / M / V]- [Q / K / R / A / E / G / L / T]. CDR3 is located 30-50 residues after end of CDR2 and following the sequence C-X-X. The length is 3-25 amino acids and is followed by the sequence [W / A / E / F / H / K / L / Q / Y / G / S / R]-[G / S]-X-G-X-X-X-T-V-S. The all the sequences, "X" can be any amino acid. Alternative CDR definitions of interest include, without limitation, Ofran et al., Almagro JC (Ofran et al. 2001, Almagro JC 2004), each of which is herein specifically incorporated by reference. Specific embodiments of the invention The present invention provides novel monoclonal binding agents comprising sdAbs able to bind and / or block and / or neutralize Elapidae three-finger toxins (3FTx) of multiple snake species, which are applicable for being used in all aspects disclosed herein. The respective amino acid sequences are summarized in Table 1: SEQ ID NO Amino acid sequence 1 LICHNQQSSQ PPTTKTCPGE TNCYKKQWRD HRGTIIERGC GCPTVKKGIK LNCCTTDKCN N RTCYKTPSDT SQICPPGENI CYTKTWCDAW CSQRGKRVEL GCAATCPKVK AGVDIKCCST 2 DNCNPFPTRK PR QVQLQESGGG SVQAGGSLRL SCTASDGSLS TYTVGWFRQV SEVGRDLVAQ SGSAGSDDED THVAGSVAGR FTISRDNTEN TVYLQMNNLT PEDTAVYYCA AAPGDHYTNW 3 GQGTQVTVSS AAADYKDHDG DYKDHDIDYK DDDDKGAAHH HHHH QVQLQESGGG VVQAGGSLRL SCAVSGVSES IFANYVVGWF RQQDSGTGRD LVAQSSSDDE YNHVSGSVKG RFTISRDNAK NTVSLQMDNV KPEDTATYIC AAALGPGDNY IYWGQGTQVT 4 VSSAAADYKD HDGDYKDHDI DYKDDDDKGA AHHHHHH QVQLQESGGG LVRPGGSLRL SCAVSGVSES IFANYVVGWF RQQDSGTGRD LVAQSSSDDE YNHVSGSVKG RFTISRDNAK NTVSLQMDNL KPEDTAIYIC AAAIGPGDNY IYWGQGTQVT 5 VSSAAADYKD HDGDYKDHDI DYKDDDDKGA AHHHHHH QVQLQESGGG LVRPGGSLRL SCAVSGVSES IFAKYVVGWF RQQDSGTGRD LVAQSSSDDE YNHVSGSVKG RFTISRDNAK NTVSLQMDNV KPEDTATYIC AAAPGPGDNY IYWGQGTQVT 6 VSSAAADYKD HDGDYKDHDI DYKDDDDKGA AHHHHHH QVQLQESGGG LVQTGGSLTL SCAASGFTFD DWAIAWFRQA PGKEREGVSV LPISDPPATA YGHFVKGRFS ISTNNARNTV YLQMNNLKPE DTAVYYCAAS RFWGSNWKDP 7 PEYDYWGQGT QVTVSSAAAD YKDHDGDYKD HDIDYKDDDD KGAAHHHHHH QVQLQESGGG LAQPGGSLSL SCATTRDVGS IHAMAWYRQA PGKQRELVAS VTMVGGETPT YAESIKGRFT ISKDNDKNAI SLQMSSLKPE DTAVYYCKAD SYCSDSACYE 8 NPVFDYWGQG TQVTVSSAAA DYKDHDGDYK DHDIDYKDDD DKGAAHHHHH H QVQLQESGGG LVQPGGSLRL SCAASGDIAG LNNMGWYRQA PGKQRELVAA QARGGNTNYT DSVKGRFTIS RDNAENTVYL QMNSLKSEDT AVYYCYAAVG NWYESGYYVD 9 DYWGQGTQVT VSSAAADYKD HDGDYKDHDI DYKDDDDKGA AHHHHHH QVQLQESGGG LVQPGGSLRL SCAASGDIGG LKQMGWYRQA PGHQRELVAV KRNENEANYT ESVKGRFTIS RDNARKMVYL QMNSLKPEDT AVYYCNAVVG NWYTSGYYED 10 TYWGQGTQVT VSSAAADYKD HDGDYKDHDI DYKDDDDKGA AHHHHHH QVQLQESGGG LVQPGGSLRL SCAASGDIVS LNVMGWYRQA PGKQRELVAI MKKDTSTTYA DSVKGRFTIS RDNANHTSSL QMNSLEPEDT AVYYCNAAGV VYQQGVYMDY 11 TKDYWGKGTQ VTVSSAAADY KDHDGDYKDH DIDYKDDDDK GAAHHHHHH 12 DGSLSTYT 13 SGSAGSDDED T 14 AAAPGDHYTN 15 GVSESIFANY V 16 SSSDDEYN 17 AAALGPGDNY IY 18 GVSESIFANY V SEQ ID NO Amino acid sequence 19 SSSDDEYN 20 AAAIGPGDNY IY 21 GVSESIFAKY V 22 SSSDDEYN 23 AAAPGPGDNY IY 24 GFTFDDWAI 25 VSVLPISDPP AT 26 AASRFWGSNW KDPPEYDY 27 RDVGSIHA 28 VASVTMVGGE TP 29 KADSYCSDSA CYENPVFDY 30 GDIAGLNN 31 VAAQARGGNT 32 YAAVGNWYES GYYVDDY 33 GDIGGLKQ 34 VAVKRNENEA 35 NAVVGNWYTS GYYEDTY 36 GDIVSLNV 37 VAIMKKDTST 38 NAAGVVYQQG VYMDYTKDY Table 1. SEQ ID Nos. The monoclonal binding agent binds the consensus Elapidae α-neurotoxin amino acid sequence SEQ ID NO: 1 or 2. The CDR1, CDR2, and CDR3 each comprises or consists of an amino acid sequence determined according to either Kabat, Chothia, IMTG or Aho numbering schemes and present in an amino acid sequence selected from any one of SEQ ID NOs: 3-11, optionally wherein the CDR1 contain 1, 2, or 3 amino acid substitutions and / or the CDR2 contain 1, 2, or 3 amino acid substitutions and / or the CDR3 contains 1, 2, or 3 amino acid substitutions, wherein substitutions preferably are conservative. Such substitutions are according to preferred embodiments of the invention made with amino acid residues of the proteinogenic amino acids, that is, substitution(s) is / are preferably made with the genetically encoded L- amino acids belonging to the group arginine, histidine, lysine, aspartic acid, glutamic acid, serine, threonine, asparagine, glutamine, glycine, proline, cysteine, alanine, valine, isoleucine, leucine, methionine, phenylalanine, tyrosine, and tryptophane, as well as with the 2 known amino acids emerging from translational recoding: selenocysteine and pyrrolysine. Typically, substitution is made with an amino acid among the 20 genetically encoded L-amino acids: arginine, histidine, lysine, aspartic acid, glutamic acid, serine, threonine, asparagine, glutamine, glycine, proline, cysteine, alanine, valine, isoleucine, leucine, methionine, phenylalanine, tyrosine, and tryptophane. The three-finger toxins (3FTx) are neurotoxins or cytotoxins. The monoclonal binding agent is able to bind, block and / or neutralise Elapidae neurotoxins, preferably α-neurotoxins of multiple snake species. The α-neurotoxins may be short-chain α-neurotoxins (SC), long-chain α-neurotoxins (LC), non-conventional α-neurotoxins (NC) or atypical α-neurotoxins of multiple snake species. SC- and LC-α-neurotoxins share a common protein fold with minor differences in length (between 60 and 62 or 66 and 75 residues, respectively), and the number and position of disulfide bonds. They both bind to and inhibit nicotinic acetylcholine receptors (nAChRs) with varying selectivity against different members of this family of receptors. Conveniently, in one embodiment the α-neurotoxins are short-chain α-neurotoxins (SC) or long-chain α-neurotoxins (LC) of multiple snake species. The short-chain α-neurotoxins (SC) or long-chain α-neurotoxins (LC) may be selected from the list comprising Short neurotoxin 1, Short neurotoxin 2, Short neurotoxin 3, Short neurotoxin 4, Short neurotoxin 5, Short neurotoxin 6, Short neurotoxin A, Short neurotoxin B, Short neurotoxin C, Short neurotoxin D, Cobrotoxin-b, α-elapitoxin-Nn2a, α-neurotoxin NTX-1, α-elapitoxin-Dpp2C, α-elapitoxin-Oh3a, Long neurotoxin 1, Long neurotoxin 2, Long neurotoxin 3, Long neurotoxin 4, α-elapitoxin-Dv2b, α-elapitoxin-Dpp2b, α-cobratoxin and α- bungarotoxin. Preferably, the short-chain α-neurotoxins (SC) or long-chain α-neurotoxins (LC) are selected from the list comprising Short neurotoxin 1 (P01416, P01417, P01418, P01424, P01426, P68418), Short neurotoxin 2 (P01433, P01423, Q9W7K1), Short neurotoxin 3 (P01432, Q9W7K0), Short neurotoxin 4 (P01421, Short neurotoxin 5 (P82849), Short neurotoxin 6 (Q9W7J7), Short neurotoxin 7 (Q9W7J6), Short neurotoxin A (P32879), Short neurotoxin B (P19959, P10459), Short neurotoxin C (P19958, P10460), Short neurotoxin D (P10456), α- neurotoxin NTX-1 (Q9YGJ6) Cobrotoxin (P60771)-b, α-elapitoxin-Nn2a (C0HM08), α- neurotoxin NTX-1 (Q9YGJ6), α-elapitoxin-Dpp2C (P01397), α-elapitoxin-Oh3a (Q53B58), Long neurotoxin 1 (P01383, P01387, P01389, P01390), Long neurotoxin 2 (P01386, P01388), Long neurotoxin 3 (P25671), Long neurotoxin 4 (P25672), α-elapitoxin-Dv2b (P01394), α-elapitoxin-Dpp2b (P25667), α-cobratoxin (P01391) and α-bungarotoxin (P60615). The Uniprot IDs are merely showing exemplary toxins and is a non-exhaustive list. Other natural or synthetic variants of toxins may also be included. In one embodiment, the monoclonal binding agent can also bind, block and / or neutralise Elapidae cytotoxins. The cytotoxins may be selected from the group comprising Cytotoxin 1, Cytotoxin, Cytotoxin 3, Cytotoxin 4, Cytotoxin 5, Cytotoxin 6, Cytotoxin 7, Cytotoxin 8, Cytotoxin 9, Cytotoxin 10, Naniproin and Hemachatoxin. Preferably, the cytotoxins may be selected from the group comprising Cytotoxin 1 (P01448, P01467, P60305, P60304, P01451, P01447), Cytotoxin 2 (P01445, P01469, P01442, P01441), Cytotoxin 3 (P01446, P60301, P01470, P24780), Cytotoxin 4 (P60303, P01452, P01443), Cytotoxin 5 (P07525, P24779, P25517), Cytotoxin 6 (P80245), Cytotoxin 7 (P86382), Cytotoxin 8 (P86540), Cytotoxin 9 (A0A0U5AUY6), Cytotoxin 10 (P86541), Naniproin (P0DSN1) and Hemachatoxin (B3EWH9). The Uniprot IDs are merely showing exemplary toxins and is a non-exhaustive list. Other natural or synthetic variants of toxins may also be included. The CDR1, CDR2 and CDR3 have the amino acid sequences: a) SEQ ID NOs: 12, 13, 14, or b) SEQ ID NOs: 15, 16, 17, or c) SEQ ID NOs: 18, 19, 20, or d) SEQ ID NOs: 21, 22, 23, or e) SEQ ID NOs: 24, 25, 26, or f) SEQ ID NOs: 27, 2829 or g) SEQ ID NOs: 30, 31, 32 or h) SEQ ID NOs: 33, 34, 35 or i) SEQ ID NOs: 36, 37, 38, wherein CDR1 optionally contains 1, 2, or 3 amino acid substitutions and / or CDR2 optionally contains 1, 2, or 3 amino acid substitutions and / or CDR3 optionally contains 1, 2, or 3 amino acid substitutions, preferably 1, 2, or 3 conservative substitutions. In an embodiment, the monoclonal binding agent is able to bind, block and / or neutralize short-chain-α-neurotoxins (SC) of multiple snake species and comprises binding regions CDR1, CDR2, and CDR3 having the respective SEQ ID Nos: 12, 13, 14, or 15, 16, 17 or 18, 19, 20, or 21, 22, 23, wherein each CDR is determined according to Aho numbering scheme, optionally wherein CDR1 contain 1, 2, or 3 amino acid substitutions, CDR2 contain 1, 2, or 3 amino acid substitutions and CDR3 contain 1, 2, or 3 amino acid substitutions. In another embodiment, the monoclonal binding agent is able to bind, block and / or neutralize long-chain-α-neurotoxins (LC) of multiple snake species and comprises binding regions CDR1, CDR2, and CDR3 having the respective SEQ ID Nos: 24, 25, 26, or 27, 28, 29, or 30, 31, 32, or 33, 34, 35, or 36, 37, 38, wherein each CDR is determined according to Aho numbering scheme, optionally wherein CDR1 contain 1, 2, or 3 amino acid substitutions, CDR2 contain 1, 2, or 3 amino acid substitutions and CDR3 contain 1, 2, or 3 amino acid substitutions. In a preferred embodiment of the previous embodiment, the binding regions CDR1, CDR2, and CDR3 have the respective SEQ ID Nos: 33, 34, and 35, optionally wherein CDR1 contains 1, 2, or 3 amino acid substitutions, CDR2 contains 1, 2, or 3 amino acid substitutions and CDR3 contains 1, 2, or 3 amino acid substitutions. In a further preferred embodiment of the previous embodiment, the monoclonal binding agent comprises aspartic acid (D) or glutamic acid (E) in position 27 of CDR1, preferably D, an aromatic amino acid residue selected from tryptophan (W), tyrosine (Y) and phenylalanine (F) in position 99 of CDR3, preferably W, and an aromatic amino acid residue selected from W, Y and F in position 100 of CDR3, preferably Y. In a preferred embodiment of the two previous embodiments, the monoclonal binding agent is able to bind to α-cobratoxin. In another embodiment, the monoclonal binding agent comprises an amino acid sequence selected from any one of SEQ ID NOs: 3-11, wherein each CDR is determined according to the Aho numbering scheme, and optionally wherein the CDR1 contains 1, 2, or 3 amino acid substitutions and / or the CDR2 contains 1, 2, or 3 amino acid substitutions and / or the CDR3 contains 1, 2, or 3 amino acid substitutions, and wherein the same amino acid sequence selected from any one of SEQ ID NOs: 3-11 comprises framework regions FR1, FR2, FR3, and FR4, wherein each FR is determined according to the Aho numbering scheme, optionally wherein the FR1 contains 1, 2, 3, 4 or 5 amino acid substitutions and / or the FR2 contains 1, 2, 3, 4 or 5 amino acid substitutions and / or the FR3 contains 1, 2, 3, 4 or 5 amino acid substitutions and / or the FR4 contains 1, 2, 3, 4 or 5 amino acid substitutions, wherein substitutions preferably are conservative. In a further embodiment of the previous embodiment, the monoclonal binding agent comprises the amino acid sequence with SEQ ID NO: 10, optionally wherein the CDR1 contains 1, 2, or 3 amino acid substitutions and / or the CDR2 contains 1, 2, or 3 amino acid substitutions and / or the CDR3 contains 1, 2, or 3 amino acid substitutions, and optionally wherein the FR1 contains 1, 2, 3, 4 or 5 amino acid substitutions and / or the FR2 contains 1, 2, 3, 4 or 5 amino acid substitutions and / or the FR3 contains 1, 2, 3, 4 or 5 amino acid substitutions and / or the FR4 contains 1, 2, 3, 4 or 5 amino acid substitutions, wherein substitutions preferably are conservative. The CDR1, CDR2, and CDR3 are typically comprised in an antibody format selected from the group consisting of IgA-like antibody formats, IgE-like antibody formats, IgG-like antibody formats, and IgM-like antibody formats, preferably human, an IgY-like antibody format, and an sdAb, an sdAb-sdAb, an sdAb-Fc fusion, multimers of sdAbs, multimers of sdAb-Fc fusions or an effective binding fragment thereof. The fragment or analogue of an antibody is selected from an Fab, an Fab', an F(ab')2, a variable fragment (Fv), a triabody, a tetrabody, a minibody, a bispecific F(ab')2, a trispecific F(ab')2, a diabody, a bispecific diabody, a single chain variable fragment (scFv), an scFv-Fc, an Fab-Fc, a VHH, a bispecific scFv, or a combination thereof, preferably a VHH. The monoclonal binding agent may further comprise a linker linking the monoclonal binding agent to an antibody format, fragment or antibody analogue. In a second aspect, the invention relates to a single domain antibody (sdAb) comprising complementary determining regions CDR1, CDR2, and CDR3, said sdAb being able to bind and / or block and / or neutralize Elapidae three-finger toxins (3FTx) of multiple snake species. The sdAb binds the consensus Elapidae α-neurotoxin amino acid sequence SEQ ID NO: 1 or 2. The CDR1, CDR2, and CDR3 each comprises or consists of an amino acid sequence determined according to either Kabat, Chothia, IMTG or Aho numbering schemes in an amino acid sequence selected from any one of SEQ ID NOs 3-11, optionally wherein the CDR1 contain 1, 2, or 3 amino acid substitutions, the CDR2 contain 1, 2, or 3 amino acid substitutions and the CDR3 contain 1, 2, or 3 amino acid substitutions. The three-finger toxins (3FTx) are neurotoxins or cytotoxins. The sdAb is able to bind, block and / or neutralise Elapidae neurotoxins, preferably α-neurotoxins of multiple snake species. The α-neurotoxins may be short-chain α-neurotoxins (SC), long-chain α-neurotoxins (LC), non-conventional α-neurotoxins (NC) or atypical α-neurotoxins of multiple snake species. In one embodiment the α-neurotoxins are short-chain α-neurotoxins (SC) or long-chain α- neurotoxins (LC) of multiple snake species. The short-chain α-neurotoxins (SC) or long-chain α-neurotoxins (LC) may be selected from the list comprising Short neurotoxin 1, Short neurotoxin 2, Short neurotoxin 3, Short neurotoxin 4, Short neurotoxin 5, Short neurotoxin 6, Short neurotoxin A, Short neurotoxin B, Short neurotoxin C, Short neurotoxin D, Cobrotoxin-b, α-elapitoxin-Nn2a, α-neurotoxin NTX-1, α-elapitoxin-Dpp2C, α-elapitoxin-Oh3a, Long neurotoxin 1, Long neurotoxin 2, Long neurotoxin 3, Long neurotoxin 4, α-elapitoxin-Dv2b, α-elapitoxin-Dpp2b, α-cobratoxin and α- bungarotoxin. Preferably, the short-chain α-neurotoxins (SC) or long-chain α-neurotoxins (LC) may be selected from the list comprising Short neurotoxin 1 (P01416, P01417, P01418, P01424, P01426, P68418), Short neurotoxin 2 (P01433, P01423, Q9W7K1), Short neurotoxin 3 (P01432, Q9W7K0), Short neurotoxin 4 (P01421, Short neurotoxin 5 (P82849), Short neurotoxin 6 (Q9W7J7), Short neurotoxin 7 (Q9W7J6), Short neurotoxin A (P32879), Short neurotoxin B (P19959, P10459), Short neurotoxin C (P19958, P10460), Short neurotoxin D (P10456), α-neurotoxin NTX-1 (Q9YGJ6) Cobrotoxin (P60771)-b, α-elapitoxin-Nn2a (C0HM08), α-neurotoxin NTX-1 (Q9YGJ6), α-elapitoxin-Dpp2C (P01397), α-elapitoxin-Oh3a (Q53B58), Long neurotoxin 1 (P01383, P01387, P01389, P01390), Long neurotoxin 2 (P01386, P01388), Long neurotoxin 3 (P25671), Long neurotoxin 4 (P25672), α-elapitoxin- Dv2b (P01394), α-elapitoxin-Dpp2b (P25667), α-cobratoxin (P01391) and α-bungarotoxin (P60615). The Uniprot IDs are merely showing exemplary toxins and is a non-exhaustive list. Other natural or synthetic variants of toxins may also be included. In one embodiment, the sdAb can also bind, block and / or neutralise Elapidae cytotoxins. The cytotoxins may be selected from the group comprising Cytotoxin 1, Cytotoxin, Cytotoxin 3, Cytotoxin 4, Cytotoxin 5, Cytotoxin 6, Cytotoxin 7, Cytotoxin 8, Cytotoxin 9, Cytotoxin 10, Naniproin and Hemachatoxin. Preferably, the cytotoxins may be selected from the group comprising Cytotoxin 1 (P01448, P01467, P60305, P60304, P01451, P01447), Cytotoxin 2 (P01445, P01469, P01442, P01441), Cytotoxin 3 (P01446, P60301, P01470, P24780), Cytotoxin 4 (P60303, P01452, P01443), Cytotoxin 5 (P07525, P24779, P25517), Cytotoxin 6 (P80245), Cytotoxin 7 (P86382), Cytotoxin 8 (P86540), Cytotoxin 9 (A0A0U5AUY6), Cytotoxin 10 (P86541), Naniproin (P0DSN1) and Hemachatoxin (B3EWH9). The CDR1, CDR2 and CDR3 have the amino acid sequences: a) SEQ ID NOs: 12, 13, 14, or b) SEQ ID NOs: 15, 16, 17, or c) SEQ ID NOs: 18, 19, 20, or d) SEQ ID NOs: 21, 22, 23, or e) SEQ ID NOs: 24, 25, 26, or f) SEQ ID NOs: 27, 2829 or g) SEQ ID NOs: 30, 31, 32 or h) SEQ ID NOs: 33, 34, 35 or i) SEQ ID NOs: 36, 37, 38, wherein CDR1 optionally contains 1, 2, or 3 amino acid substitutions and / or CDR2 optionally contains 1, 2, or 3 amino acid substitutions and / or CDR3 optionally contains 1, 2, or 3 amino acid substitutions, preferably 1, 2, or 3 conservative substitutions. In an embodiment, the sdAb is able to bind, block and / or neutralize short-chain-α- neurotoxins (SC) of multiple snake species and comprises binding regions CDR1, CDR2, and CDR3 having the respective SEQ ID Nos: 12, 13, 14, or 15, 16, 17 or 18, 19, 20, or 21, 22, 23, wherein each CDR is determined according to Aho numbering scheme, optionally wherein CDR1 contain 1, 2, or 3 amino acid substitutions, CDR2 contain 1, 2, or 3 amino acid substitutions and CDR3 contain 1, 2, or 3 amino acid substitutions. In another embodiment, the sdAb is able to bind, block and / or neutralize long-chain-α- neurotoxins (LC) of multiple snake species and comprises binding regions CDR1, CDR2, and CDR3 having the respective SEQ ID Nos: 24, 25, 26, or 27, 28, 29, or 30, 31, 32, or 33, 34, 35, or 36, 37, 38, wherein each CDR is determined according to Aho numbering scheme, optionally wherein CDR1 contain 1, 2, or 3 amino acid substitutions, CDR2 contain 1, 2, or 3 amino acid substitutions and CDR3 contain 1, 2, or 3 amino acid substitutions. In a preferred embodiment of the previous embodiment, the binding regions CDR1, CDR2, and CDR3 have the respective SEQ ID Nos: 33, 34, and 35, optionally wherein CDR1 contains 1, 2, or 3 amino acid substitutions, CDR2 contains 1, 2, or 3 amino acid substitutions and CDR3 contains 1, 2, or 3 amino acid substitutions. In a further preferred embodiment of the previous embodiment, the sdAb comprises aspartic acid (D) or glutamic acid (E) in position 27 of CDR1, preferably D, an aromatic amino acid residue selected from tryptophan (W), tyrosine (Y) and phenylalanine (F) in position 99 of CDR3, preferably W, and an aromatic amino acid residue selected from W, Y and F in position 100 of CDR3, preferably Y. In a preferred embodiment of the two previous embodiments, the sdAb is able to bind to α- cobratoxin. In another embodiment, the sdAb comprises an amino acid sequence selected from any one of SEQ ID NOs: 3-11, wherein each CDR is determined according to the Aho numbering scheme, and optionally wherein the CDR1 contains 1, 2, or 3 amino acid substitutions and / or the CDR2 contains 1, 2, or 3 amino acid substitutions and / or the CDR3 contains 1, 2, or 3 amino acid substitutions, and wherein the same amino acid sequence selected from any one of SEQ ID NOs: 3-11 comprises framework regions FR1, FR2, FR3, and FR4, wherein each FR is determined according to the Aho numbering scheme, optionally wherein the FR1 contains 1, 2, 3, 4 or 5 amino acid substitutions and / or the FR2 contains 1, 2, 3, 4 or 5 amino acid substitutions and / or the FR3 contains 1, 2, 3, 4 or 5 amino acid substitutions and / or the FR4 contains 1, 2, 3, 4 or 5 amino acid substitutions, wherein substitutions preferably are conservative. In a further embodiment of the previous embodiment, the sdAb comprises the amino acid sequence with SEQ ID NO: 10, optionally wherein the CDR1 contains 1, 2, or 3 amino acid substitutions and / or the CDR2 contains 1, 2, or 3 amino acid substitutions and / or the CDR3 contains 1, 2, or 3 amino acid substitutions, and optionally wherein the FR1 contains 1, 2, 3, 4 or 5 amino acid substitutions and / or the FR2 contains 1, 2, 3, 4 or 5 amino acid substitutions and / or the FR3 contains 1, 2, 3, 4 or 5 amino acid substitutions and / or the FR4 contains 1, 2, 3, 4 or 5 amino acid substitutions, wherein substitutions preferably are conservative. In a third aspect, the invention relates to a pharmaceutical composition comprising the monoclonal binding agent according to the first aspect or one or more sdAb according to the second aspect, wherein the composition further comprises a pharmaceutically acceptable carrier and / or vehicle and / or diluent and / or excipient. The pharmaceutical composition may be a liquid, a semi-solid, or a solid dosage form. Preferably, the composition is formulated for being administered by injection, such as intravenous, sub-cutaneous, or intramuscular injection. In a fourth aspect, the invention relates to a method for treatment of snake envenomation, the method comprising administering an effective amount of the monoclonal binding agent according to the first aspect or one or more sdAb according to the second aspect or the pharmaceutical composition according to the third aspect. In a fifth aspect, the invention relates to the monoclonal binding agent according to the first aspect, one or more sdAb according to the second aspect or the pharmaceutical composition according to the third aspect for use as a medicament, preferably for use in the treatment or prevention of snake envenomation. In a sixth aspect, the invention relates to a method of producing a monoclonal binding agent according to the first aspect or one or more sdAb according to the second aspect, the method comprising the step of: screening an sdAb-displaying phage library against a polypeptide comprising or consisting of a consensus sequence of at least 2 distinct three-finger toxins (3FTxs) from multiple Elapidae snake species; and isolating sdAb species from the library that bind the polypeptide and selecting from these isolated sdAb species those that verifiably bind to Elapidae three-finger toxins (3FTx) of multiple snake species, and if necessary, grafting CDR sequences from the selected sdAb species to obtain a monoclonal binding agent as defined the first aspect. The method further comprises: a) immunizing one or more sdAb-harbouring animal(s), such as camelid(s), with toxins, such as complete snake venom, from multiple Elapidae snake species to induce production of sdAbs against the toxins in the one or more animals, b) deriving, from the one or more immunized animals in the nucleic acid sequences for sdAbs induced in the animals, c) creating a phage library expressing the nucleic acid sequences encoding the sdAbs and thereby displaying the sdAbs and d) screening the sdAb-displaying phage library against a polypeptide comprising or consisting of a consensus sequence of at least 2 distinct three-finger toxins (3FTxs) from multiple Elapidae snake species. In yet another embodiment, the method further comprises the step of: identifying the sdAb coding sequences of phages binding to the polypeptide comprising or consisting of a consensus sequence of at least 2 distinct three-finger toxins (3FTxs) from multiple Elapidae snake species. The consensus sequence is constructed by aligning the sequence of at least two distinct three-finger toxins from multiple Elapidae snake species and by determining the consensus amino acid sequences depending on the amino acid abundance. For each position, the most repeated amino acid was kept, and in case of a tie, the most abundant amino acid within the most present physicochemical property (acid – (E, D), basic (K, R), polar (S, T, Y, N, N), non-polar (G, A, V, L, I, M, W, F). Proline (P) and cysteine (C) formed a group themselves. The three-finger toxins are neurotoxins, preferably α-neurotoxins of multiple snake species. The α-neurotoxins are short-chain α-neurotoxins (SC), long-chain α-neurotoxins (LC), non- conventional α-neurotoxins (NC) or atypical α-neurotoxins of multiple snake species. The α-neurotoxins are short-chain α-neurotoxins (SC) or long-chain α-neurotoxins (LC) of multiple snake species. The short-chain α-neurotoxins (SC) or long-chain α-neurotoxins (LC) may be selected from the list comprising Short neurotoxin 1, Short neurotoxin 2, Short neurotoxin 3, Short neurotoxin 4, Short neurotoxin 5, Short neurotoxin 6, Short neurotoxin A, Short neurotoxin B, Short neurotoxin C, Short neurotoxin D, Cobrotoxin-b, α-elapitoxin- Nn2a, α-neurotoxin NTX-1, α-elapitoxin-Dpp2C, α-elapitoxin-Oh3a, Long neurotoxin 1, Long neurotoxin 2, Long neurotoxin 3, Long neurotoxin 4, α-elapitoxin-Dv2b, α-elapitoxin-Dpp2b, α-cobratoxin and α-bungarotoxin. Preferably, the short-chain α-neurotoxins (SC) or long-chain α-neurotoxins (LC) may be selected from the list comprising Short neurotoxin 1 (P01416, P01417, P01418, P01424, P01426, P68418), Short neurotoxin 2 (P01433, P01423, Q9W7K1), Short neurotoxin 3 (P01432, Q9W7K0), Short neurotoxin 4 (P01421, Short neurotoxin 5 (P82849), Short neurotoxin 6 (Q9W7J7), Short neurotoxin 7 (Q9W7J6), Short neurotoxin A (P32879), Short neurotoxin B (P19959, P10459), Short neurotoxin C (P19958, P10460), Short neurotoxin D (P10456), α-neurotoxin NTX-1 (Q9YGJ6) Cobrotoxin (P60771), α-elapitoxin-Nn2a (C0HM08), α-neurotoxin NTX-1 (Q9YGJ6), α-elapitoxin-Dpp2C (P01397), α-elapitoxin-Oh3a (Q53B58), Long neurotoxin 1 (P01383, P01387, P01389, P01390), Long neurotoxin 2 (P01386, P01388), Long neurotoxin 3 (P25671), Long neurotoxin 4 (P25672), α-elapitoxin-Dv2b (P01394), α-elapitoxin-Dpp2b (P25667), α-cobratoxin (P01391) and α-bungarotoxin (P60615). In one embodiment, the sdAb can also bind, block and / or neutralise Elapidae cytotoxins. The cytotoxins may be selected from the group comprising Cytotoxin 1, Cytotoxin, Cytotoxin 3, Cytotoxin 4, Cytotoxin 5, Cytotoxin 6, Cytotoxin 7, Cytotoxin 8, Cytotoxin 9, Cytotoxin 10, Naniproin and Hemachatoxin. Preferably, the cytotoxins may be selected from the group comprising Cytotoxin 1 (P01448, P01467, P60305, P60304, P01451, P01447), Cytotoxin 2 (P01445, P01469, P01442, P01441), Cytotoxin 3 (P01446, P60301, P01470, P24780), Cytotoxin 4 (P60303, P01452, P01443), Cytotoxin 5 (P07525, P24779, P25517), Cytotoxin 6 (P80245), Cytotoxin 7 (P86382), Cytotoxin 8 (P86540), Cytotoxin 9 (A0A0U5AUY6), Cytotoxin 10 (P86541), Naniproin (P0DSN1) and Hemachatoxin (B3EWH9). The at least 2 distinct three-finger neurotoxins are α-neurotoxins, wherein the α-neurotoxins are short-chain α-neurotoxins (SC), long-chain α-neurotoxins (LC), non-conventional α- neurotoxins (NC) or atypical α-neurotoxins of multiple snake species. In a seventh aspect, the invention relates to the monoclonal binding agent according to the first aspect or one or more sdAbs according to the second aspect for use in a method of diagnosis of snake envenomation in a subject affected thereof. Generally, antibodies and antibody fragments and analogues are useful molecules in a number of detection methods, which find use in e.g., diagnostics. Hence, the monoclonal binding agents of the present invention can be utilized in any of a large number of detection methods that rely on the ability of the monoclonal binding agents to bind to the toxins discussed herein. Such detection methods can rely on direct detection of toxin (as would be the case in an agglutination assay where sample is admixed with dilution of the monoclonal binding agents) or indirect detection where labelled antibodies specific for the monoclonal binding agents are contacted with these after binding to toxins has been facilitated, e.g., in a sandwich assay format. Also competitive assay formats can be utilised where sample potentially comprising toxin is contacted with labelled toxin bound to the monoclonal binding agents and where displacement of the labelled toxin is determined; one particularly sensitive version can be established if both the monoclonal binding agent and the toxin are labelled so that the signal is quenched by the competing sample toxin binding to the monoclonal binding agent or if the labels in the toxin and monoclonal binding agent constitute a donor and acceptor in a FRET pair. Detection of toxin in a sample can be achieved by using assays in the form of radioimmune assays (RIA), enzyme-linked immunosorbent assays (ELISA) etc, but also direct interaction can be detected via e.g., plasmon resonance or FRET as indicated above. In some assay formats of interest, the monoclonal binding agents are coupled to a solid phase, such as beads (e.g., magnetic beads), a hollow fibre, the wall and / or bottom of a microtiter well, a sponge, a strip etc. In one particularly interesting embodiment, the method of diagnosis comprises providing a diagnostic kit comprising a lateral flow assay, or an enzyme-linked immunosorbed (ELISA) assay for the detection and identification of snake envenomation in a subject. In all of the above aspects and embodiments, the Elapidae snake are selected from the genus comprising Dendroaspis sp., Naja sp., Hemachatus sp., Bungarus sp., Aspidelaps sp., Micrurus sp., Ophiophagus sp. In all of the above aspects and embodiments, the Elapidae snake species may be selected from the group comprising D. angusticeps, D. jamesoni, D. polylepis, D. viridis, N. anchietae, N. annulifera, N. ashei, N. haje, N. katiensis, N. melanoleuca, N. mossambica, N. nigricincta, N. nigricollis, N. nubiae, N. pallida, N. senegalensis, and H. haemachatus. EXAMPLE 1 Materials and methods Construction of consensus toxins Amino acid sequences of SC- and LC-α-neurotoxin from African snakes were obtained from UniProt (http: / / www.uniprot.org). SnapGene® software (from Insightful Science; available at snapgene.com) was used to perform multiple alignments of either 20 or 14 sequences of SC- α-neurotoxin or LC-α-neurotoxin, respectively, and from the two alignments, two consensus amino acid sequences were determined: short-chain consensus (SCC) and long-chain consensus (LCC). The consensus sequence was built by taking decisions for each position depending on the amino acid abundance. For each position, the most repeated amino acid was kept, and in case of a tie, the most abundant amino acid within the most present physicochemical property (acid – (E, D), basic (K, R), polar (S, T, Y, N, N), non-polar (G, A, V, L, I, M, W, F). Proline (P) and cysteine (C) formed a group themselves. Plasmid construction for toxin expression The genes for the consensus toxins were purchased from Eurofins and cloned into a plasmid. The genes encoding the 6xHis-consensus toxin were inserted into a pPICZα A vector (Invitrogen) using the NEBuilder HiFi DNA Assembly method. The resulting plasmids were verified by DNA sequencing to confirm the correct insertion (Eurofins Genomics Sanger sequencing service, Ebersberg, Germany). Expression and purification of consensus toxins The expression and purification of the two consensus toxins followed a previously described protocol. Briefly, Komagataella phaffii (previously known as Pichia pastoris) KM71H were electroporated with the Sanger-sequenced confirmed plasmid, and positive transformants were identified by plating on YPDS plates (20 g / L Peptone, 10 g / L Yeast Extract, 100 mL / L Dextrose 20% (w / v), 182.2 g / L Sorbitol, 20g / L Agar) containing 1000 ug / mL of Zeocin. Following a preliminary assessment of small-scale expression, colonies exhibiting higher toxin production, as determined by SDS-PAGE analysis of culture supernatants, were selected. Subsequently, the selected recombinant toxins were cultured in YPD medium overnight at 30°C. To ensure long-term preservation, 15% (v / v) glycerol was added to the cultures, which were then aliquoted and stored at -80 °C. A 5 mL overnight culture of the selected clone in YPD medium (20 g / L Peptone, 10 g / L Yeast Extract, 20% (w / v) Dextrose) was inoculated with a single colony of transformed P. pastoris and incubated overnight at 30 °C. The culture was then scaled up to 1 L of BMGY medium (10 g / L Yeast Extract, 20 g / L Peptone, 0.1 M Potassium phosphate pH 6.0, 1.34% (w / v) YNB, 0.04 μg / mL Biotin, 1% (v / v) Glycerol) and grown for 24 hours at 30°C. The cells were harvested, resuspended in BMMY medium (10 g / L Yeast Extract, 20 g / L Peptone, 0.1 M Potassium phosphate pH 6.0, 1.34% (w / v) YNB, 0.04 μg / mL Biotin, 0.5% (v / v) Methanol), and cultured at 25 °C for 4 days with methanol induction. After 96 hours, the cells were harvested, and the supernatant was collected and sterilized by filtration. The filtered supernatant was dialyzed against wash buffer (50 mM Tris-HCl, pH 8.0, 300 mM NaCl, 20 mM imidazole) and purified using HIS-Select® Nickel Affinity Gel resin. The consensus toxins were eluted with elution buffer (50 mM Tris-HCl, pH 8.0, 300 mM NaCl, 400 mM imidazole), dialyzed against a dialysis buffer (50 mM Tris-HCl, pH 8.0, 300 mM NaCl), and concentrated using Amicon® Ultra-15 Centrifugal Filters (Millipore, Burlington, USA). The supernatant and purification steps samples were run on a sodium dodecyl sulfate- polyacrylamide gel electrophoresis (SDS-PAGE) gel and stained with colloidal Coomassie blue. Native toxin preparation Lyophilized forms of short neurotoxin 1 (L8101), α-cobratoxin (L8114), α-Bungarotoxin (L8115) and whole venom derived from Dendroaspis jamesoni (L1308), D. polylepis (L1309), D. viridis (L1310) Hemachatus haemachatus (L1311), Naja annulifera (L1314), N. haje (L1315), N. melanoleuca (L1318), N. nivea (L1328) were obtained from Latoxan SAS (Portes- lès-Valence, France) and prepared following established procedures. The whole venom underwent fractionation using RP-HPLC to isolate fractions enriched with either SC- or LC-α- neurotoxins. In vitro biotinylation of toxins The toxins, both consensus and native, were subjected to biotinylation, following a previously established protocol, using a molar ratio of 1:1 (toxin:biotinylation reagent). To purify and concentrate the biotinylated toxins, Amicon® Ultra-4 Centrifugal Filter Units (Millipore, Burlington, USA) equipped with a 3 kDa membrane cut-off were employed. The degree of biotinylation was assessed using MALDI-TOF analysis performed on an Ultraflex II TOF / TOF spectrometer (Bruker Daltonics, Billerica, USA). Phage display selection campaigns Phage display selection was conducted using an immune nanobody library. To generate the nanobody-displaying phage libraries, two camelids were immunized with a mixture of 18 elapid venoms (D. angusticeps, D. jamesoni, D. polylepis, D. viridis, N. anchietae, N. annulifera, N. ashei, N. haje, N. katiensis, N. melanoleuca, N. mossambica, N. nigricincta, N. nigricollis, N. nubiae, N. pallida, N. senegalensis, and H. haemachatus) over a 16-week period, followed by three booster injections within a 6-week period after a year to enhance the immune response. The libraries were constructed as described previously by Pardon et al. The resulting libraries exhibited a diversity of 5·108 and 1.6·108 individual clones, respectively. The two libraries were mixed before usage. The selection process followed a previously described methodology with a modification in the technique for capturing biotinylated toxins. Instead of direct coating onto a 96-well microtiter plate, the biotinylated toxins were captured on streptavidin-coated beads (Dynabeads M-280, Invitrogen, Waltham, MA, USA). Three consecutive rounds of selections were performed using 50 nM of the consensus toxins in the two first rounds, while in the third round, the concentration was reduced to 5 nM. The enrichment of phages achieved with two rounds with LCC as the antigen was considered sufficient, leading to the decision to perform only two selection rounds with this antigen. The selection using LCC was designated as TPL1158, while the selection using SCC was named TPL1163, referring to the respective phage display campaigns. Subcloning and initial screening of the nanobodies The nanobody encoding genes obtained from TPL1158 and TPL1163 were subcloned into the pBDS100 expression vector for nanobodies. This subcloning process involved the use of Eco91I and PstI restriction enzymes, followed by transformation into the E. coli BL21(DE3) strain. The pBDS100 vector enables the production of nanobodies with a C-terminal 3xFLAG tag and a 6xHis tag. From the two subcloned selection outputs, colonies were picked, and clones were expressed individually in 96-well plates in 150 μL autoinduction media at 30 °C overnight. 50 μL of the supernatant from the expression was left to bind on black MaxiSorp plates (Nunc A / S, Roskilde, Denmark) coated with anti-FLAG M2 at a concentration of 2.5 μg / mL. Following extensive washing with PBS-T (PBS with 0.1% Tween-20) and PBS, the binding of the nanobodies towards 20 nM SCC or LCC was evaluated using a dissociation-enhanced lanthanide fluorescence immunoassay (DELFIA).13 Detection was accomplished using streptavidin conjugated with Europium (Eu-Streptavidin) at a concentration of 0.2 μg / mL. Screening and sequencing of the nanobodies A subset of clones having a signal greater than 10 times the background was cherry-picked and subjected to a DELFIA assay to determine their capability to recognize native toxins. In total 88 clones from TPL1158 and 76 from TPL1163 were selected. The clones from the TPL1158 selection were screened against α-cobratoxin (N. kaouthia), venom fractions containing primary LC-α-neurotoxins (fraction 8 from N. nivea (Nn8) and fraction 4 from D. viridis (Dv4)), short neurotoxin 1 (N. pallida), and streptavidin. Conversely, the clones from the TPL1163 selection were screened against short neurotoxin 1 (N. pallida), venom fractions enriched with primary SC-α-neurotoxins (fraction 4 from N. nivea (Nn4), fraction 4 from D. polylepis (Dp4), and fraction 1 from D. viridis (Dv1)), α-cobratoxin (N. kaouthia), and streptavidin. The chosen clones were subjected to expression in a 96-deep well plate using a 1 mL autoinduction media, allowing for overnight incubation at 30°C. The following day, the plates were centrifuged at 4,000 × g for 15 minutes at 4 °C, and subsequently frozen for 24 hours. After thawing on ice, the cell pellets were reconstituted in 110 μL of PBS supplemented with complete EDTA-free Protease Inhibitor (Roche). Another centrifugation step at 4,000×g at 4 °C for 30 minutes was performed to collect the supernatant, which contained the periplasmic fraction along with the nanobodies. 60 μL of the periplasmic fraction containing nanobodies was diluted 1 / 100 in 3% Milk-PBS. The diluted periplasmic fraction was then added to black MaxiSorp plates (Nunc A / S, Roskilde, Denmark) coated with anti-FLAG M2 at a concentration of 2.5 μg / mL. The plates were blocked with 3% milk-PBS and thoroughly washed with PBS-T and PBS before 25 nM of the indicated biotinylated toxins were added and detected using Eu- Streptavidin at a concentration of 0.2 μg / mL. The selected clones were subsequently sent for sequencing (Eurofins Genomics Sanger sequencing service, Ebersberg, Germany). Purification of nanobodies Twenty-eight nanobodies were selected and expressed in 5 mL autoinduction media at 30 °C overnight. After centrifugation at 4,000 × g for 10 minutes at 4 °C, the cell pellets were frozen at -20 °C overnight. The pellets were thawed on ice and resuspended in 1 mL ice-cold PBS supplemented with complete EDTA-free Protease Inhibitor (Roche) and 10 mM imidazole. Following a centrifugation step at 20,000 × g for 45 minutes at 4 °C, the supernatant containing nanobodies was collected. Nickel affinity chromatography was performed by incubating the supernatant with HIS- Select® Nickel Affinity Gel resin (Millipore) preequilibrated with wash buffer (PBS, 20 mM imidazole, pH 8.0). After 1 hour incubation at 4 °C with end-over-end rotation, the resin was transferred to chromatography columns, and the flow-through fractions were collected. The column was washed with 6 column volumes of wash buffer, and nanobodies were eluted using 500 μL elution buffer (PBS, 250 mM imidazole, pH 8.0). Elution fractions containing the nanobodies were dialyzed twice against PBS at 4 °C to remove the imidazole. The purified nanobodies were then ready for downstream applications and further characterization. The purified nanobodies were run on an SDS-PAGE gel and stained with colloidal Coomassie blue to confirm their purity. Measurement of binding affinities of nanobodies using BLI (biolayer interferometry) The binding affinities of the selected clones were determined using the Octet K2 system (FortéBio, Fremont, CA, USA). The measurements were conducted in 96-well black microplates (655209, Greiner Bio-One, Kremsmünster, Upper Austria) at 25 °C with agitation at 1000 rpm. 1×kinetics buffer (1×KB, 18–1105, Sartorius) was prepared in PBS and used as the running buffer in the experiment. Prior to the experiment streptavidin Biosensors (18– 5019, Sartorius, Göttingen, Germany) were dipped in 1×KB for at least 10 minutes, followed by loading of the biosensors with the biotinylated toxins (ligand) at a concentration of 1 μg / mL. A brief acid conditioning step with glycine buffer (10 nM, pH 2.0) followed by neutralization in 1×KB was carried out for 5 seconds x 5 cycles. Next, a baseline was established in 1×KB for 120 seconds and the biosensors were immersed in wells containing nanobodies from 9.4–300 nM in a 2-fold dilution in 1×KB for 600 seconds, followed by a dissociation step of 900 seconds in 1×KB. The biosensors were regenerated using glycine buffer pH 2.0 for 10 seconds x 7 cycles between rounds. ForteBio’s data analysis software was used to fit the curves to a 1:1 binding model to derive the kinetic constants (global fitting model). Cross-binding assessment of nanobodies using DELFIA To assess the cross-binding capabilities of the top 9 nanobodies, binding experiments were conducted against a range of α-neurotoxins. The nanobodies discovered against SCC were assessed for binding to seven different SC-α-neurotoxins and venom fractions enriched for SC-α-neurotoxins. The nanobodies discovered against LCC were evaluated for binding to six different LC-α-neurotoxins and venom fractions enriched for LC-α-neurotoxins. Additionally, one cytotoxin with a three-finger fold was included in the testing panel against all nanobodies. A detailed compilation of the toxins employed in this analysis can be found in Table 2 below. The table provides information on the toxins and venom fractions utilised, including the snake species from which the venom was obtained and their geographical distribution. The UniProt accession number, common toxin name, and toxin family are listed for the major components present in each venom fraction. The number associated with the toxin abbreviation corresponds to the fraction peak obtained during venom purification using RP-HPLC: Toxin Snake Geographical UniProt no. Common toxin Toxin abb. species location names family Dp7 Dendroaspis Sub-Saharan P01397 + α-elapitoxin- 3FTx Long- polylepis Africa P00982 Dpp2C + δ-DTX chain αNTx + Venom kunitz type Dv4 D. viridis West Africa P00983 + Mambaquaretin-7 venom P18328 + + muscarinic toxin Kunitz-type P01397 2 + α-elapitoxin + 3FTx Dpp2c short-chain Aminergic toxin + 3FTx long-chain αNTx Dv6 D. viridis West Africa P01397 + α-elapitoxin Dpp2c 3FTx Long- F8J2H1 + Putative short chain αNTx + chain NTX 61R unknown 3FTx α-cbtx N. kaouthia South and P01391 α-cobratoxin 3FTx long- Southeast Asia chain αNTx α-btx Bungarus Southeast Asia P60615 α-Bungarotoxin 3FTx long- multicinctus chain αNTx The evaluation of nanobody binding was conducted using a DELFIA assay, as described above. In the assay, 30 nM of each nanobody was captured using anti-FLAG antibodies. To evaluate the binding of the nanobodies to different toxins, varying concentrations of the toxins were tested, ranging from 16 pM to 250 nM. Each nanobody was tested in triplicate for each toxin concentration. The results were analyzed and plotted using GraphPad Prism 9 (log(agonist) vs. response – variable slope). Assessment of toxin neutralization using DELFIA A blocking DELFIA was performed to assess the ability of selected nanobodies to prevent long- chain α-neurotoxins from binding to the human α7-acetylcholine receptor chimera, following a previously described protocol (Ledsgaard et al., mAbs, 2022). Briefly, Black MaxiSorp plates (Nunc A / S, Roskilde, Denmark) were coated with 5 μg / mL α7-AChR in PBS (500 ng / well). The plates were washed thrice with PBS-T and blocked using 3% MPBS. Mixtures of 0.1 μg / mL of biotinylated toxin with various concentrations of nanobodies or a negative control nanobody specific to cytotoxins were prepared in 3% MPBS and pre-incubated for 30 minutes at room temperature. Plates were thoroughly washed, before 50 μL of the toxin:nanobody mixture was added to the wells. The signal was generated with europium-labelled streptavidin at a concentration of 0.2 μg / mL and detected using a VICTOR Nivo Multimode Microplate reader. Measurements were performed in duplicates. The data was analysed in Graphpad Prism 10 (GraphPad Software) with a nonlinear fit using ‘ECanything’, a variable slope model, while constraining the F-value to 50. Assessment of toxin neutralization using automated patch-clamp To evaluate the potential of the nanobodies to neutralize the blocking effects of different α- neurotoxins on the muscle-type nAChR, we employed the Qube 384 automated patch-clamp platform (Sophion Bioscience), following a previously established method. Human-derived rhabdomyosarcoma RD cells, endogenously expressing the α1, β1, δ, γ, and ε subunits of nAChR, were patch-clamped for the experiments. To determine the concentration of the toxins, inhibiting 80% of a nAChR-mediated current (IC80), we elicited a current using 70 μM acetylcholine (ACh), followed by toxin administration and measurement of their inhibitory effects. To ensure full toxin effect, we preincubated with toxin for at least 5 minutes before the addition of ACh. For testing nanobody neutralization, various concentrations of the nanobodies were preincubated with toxins. The chosen toxin concentrations ranged between IC10 and IC90, allowing for a toxin:nanobody molar ratio between 1:3 and 3:1. The inhibitory effect was quantified by normalizing the elicited current to that of the initial ACh addition. Data analysis was performed using the Sophion Analyzer (Sophion Bioscience) and GraphPad Prism (GraphPad Software). In vivo neutralisation of ɑ-cobratoxin toxicity Groups of three CD1 mice between 18 and 20 g of total body weight and indistinct sex were used for in vivo Median Lethal Dose (LD50) determination and lethality neutralisation experiments. The mice were kept under 12 h light and dark cycles with food and water ad libitum. All animals and in vivo methodologies used were approved by the bioethics committee of the IBt-UNAM under project #345. The LD50 of α-cobratoxin was determined through the intravenous (i.v.) route injecting groups of mice with varying doses of the toxin in a final volume of 200 µL PBS. The percentage of dead mice was determined 24 h after injection. Data was analysed using a non-linear regression (semi-logarithmic dose-response curve) using the software GraphPad Prism 10 (GraphPad Software). For preincubation experiments, 3 LD50s of α-cobratoxin were combined with each of the nanobodies at a 1:1 toxin to nanobody molar ratio in a total volume of 200 µL of PBS. The mixture was preincubated at 37 °C for 30 min before i.v. injection into groups of 3 mice. The percentage of survival was determined 24 h after injection and graphed in Kaplan-Meier survival curves using GraphPad Prism 10 (GraphPad Software). All mice were observed during the first 5 h and then approximately every 6 h for appearance of any signs of envenomation. To estimate the significance of the results obtained in the in vivo experiments, a Mantel-Cox log-rank test was performed (Bewick et al., Critical Care, 2004). Data were compared to the negative control (PBS only) and the significance value was set to α = 0.05. Co-crystallization of nanobody and ɑ-cobratoxin Lyophilized α-cobratoxin was dissolved in a buffer of 5 mM Tris and 20 mM NaCl at pH 8.0 to a concentration of 10 mg / mL. The nanobody (VHH) TPL1158_01_C09 was then added at a 1:3 molar ratio to α-cobratoxin and allowed to bind overnight at 4 °C. For purification, the mixture was processed through an NGC QuestTM 10 Plus Chromatography system (Biorad) using a Superdex 7510 / 300GL column (Cytiva) at 4 °C with the same buffer as the mobile phase. Before analysis, the concentration of the VHH:α-cobratoxin complex was increased to 15.2 mg / mL using 3.0 kDa MWCO ultracentrifugation units (UFC500324, Merck). Crystallisation was performed using the sitting drop vapour diffusion method at 21 °C. Drops were set up either at a 2:1, 1:1, or 1:2 molar ratio of reservoir to protein in a total volume of 0.3 µL in a 96-well drop format on SWISSCI MRC 2 Well Crystallisation Plates (JENA) using Index screening solutions (Hampton Research). The wells were sealed with crystal clear tape and equilibrated against 50 uL of reservoir solution. Small crystals appeared in the 1:2 condition (25 % (w / v) PEG1500) within 48 h. Crystals developed were harvested using mounted CryoLoops (Hampton Research) with cryoprotection performed by adding glycerol to a neighbour drop with no crystals to a final concentration of 20%. A 300 µm loop was used to fish several crystals. The loop edge was kept in contact with the cryo solution for approx. 5 s to equilibrate before flash freezing the crystal in liquid nitrogen and shipping these to the beamline for remote data collection. Data collection and structure determination Diffraction data were obtained at the Biomax (MAX IV synchrotron facility, Lund, Sweden) beamline. A complete dataset was collected at 360° of which the data was processed from 190° (1900 images), using XDSAPP3 (Krug et al., J Appl Cryst., 2012; Kabsch et al., Acta Cryst. D., 2010; Adams et al., Acta Crystallogr. D. Biol. Crystallogr., 2010). The data is summarized in Table 3. The structure of the nanobody and ɑ-cobratoxin was determined by molecular replacement with Phaser-MR (McCoy, J. Appl. Cryst., 2007) using an alphafold model of the nanobody and PDB ID 7ULG as a search model. Model building and refinement were performed with Phenix.refine (Adams et al., Acta Crystallogr. D. Biol. Crystallogr., 2010) and Coot (Emsley et al., Acta Cryst. D., 2010). The structure was evaluated using MolProbity with final statistics presented in Table 3. Molecular graphics were presented with PyMOL Molecular Graphics System (Version 2.2r7pre, Schrödinger, LLC). Coordinates / structure factors have been submitted to the PDB database with the accession code 9GCN. Table 3 shows data collection and refinement statistics for the TPL01158_01_C09 and α- cobratoxin complex (*statistics for the highest-resolution shell are shown in parentheses): TPL01158_01_C09 - α-cobratoxin Wavelength0.9736Resolution range37.75 - 2.806 (2.95 - 2.81)Space groupP 1 21 1Unit cell65.2885.9475.789094.8990 Total reflections129349 (18793)Unique reflections35844 (5161)Multiplicity3.6 (3.6)Completeness (%)99.60 (99.41)Mean I / sigma(I)3.56 (0.68)Wilson B-factor62.29R-merge0.28 (>1)R-meas0.34 (>1)R-pim0.1778 (>1)CC1 / 20.984 (0.39) CC*0.996 (0.749) Reflections used in refinement20465 (2885)Reflections used for R-free1024 (145)R-work0.2712 (0.4097) R-free0.2981 (0.3985) CC(work)5786CC(free)5784Number of non-hydrogen atoms0macromolecules2ligands752solvent0.005Protein residues0.87RMS(bonds)89.81RMS(angles)8.56Ramachandran favored (%)1.63Ramachandran allowed (%)4.11Ramachandran outliers (%)14.86Rotamer outliers (%)76.25Clashscore76.26Average B-factor57.34macromolecules37.75 - 2.806 (2.95 - 2.81)solventP 1 21 1Number of TLS groups65.28 85.94 75.78 90 94.89 90 Molecular dynamics As starting structures for molecular dynamics simulations, the available X-ray structure of TPL1158_01_C09 in complex with ɑ-cobratoxin (this study) was used. In addition, TPL1158_01_C09 in complexes with α-bungarotoxin, α-neurotoxin and LCC (presented in this study) were modelled using the X-ray structure as template. To characterise and quantify the interactions and dynamics of the VHH:toxin complexes, five repetitions of 500 ns of molecular dynamics (MD) simulations were performed. MD simulations were performed in an NpT ensemble using pmemd.cuda (Salomon-Ferrer, J. Chem. Theory Comput., 2013). Bonds involving hydrogen atoms were restrained by applying the SHAKE algorithm (Miyamoto et al., Journal of Computational Chemistry, 1992), allowing a time step of 2 fs. The complexes were placed into cubic water boxes of TIP3P water molecules (Jorgensen et al., The Journal of Chemical Physics, 1983) with a minimum wall distance to the protein of 12 Å (El Hage et al., Elife, 2018; Gapsys et al., Elife, 2019). Parameters for all simulations were derived from the AMBER force field 14SB (Maier et al., J. Chem. Theory Comput., 2015). To neutralise the charges, we used uniform background charges (Darden et al., The Journal of Chemical Physics, 1993; Salomon-Ferrer et al., WIREs Computational Molecular Science, 2013; Hub et al., J. Chem. Theory Comput., 2014). Each system was carefully equilibrated using a multistep equilibration protocol (Wallnoefer et al., J. Phys. Chem., 2010). Atmospheric pressure of the system was preserved by weak coupling to an external bath using the Berendsen algorithm (Berendsen et al., The Journal of Chemical Physics, 1984). The Langevin thermostat was used to maintain the temperature during simulations at 300 K (Doll et al., The Journal of Chemical Physics, 1975; Adelman et al., The Journal of Chemical Physics, 1976). The interactions were calculated using the GetContacts tool, which calculates the interface contacts in a time-resolved way and allows to monitor the evolution of contacts during the simulation. The hydrogen bonds from the X-ray structure have been calculated using a heavy-atom distance criterion of 3.5 Å. Molecular graphics were presented with the PyMOL Molecular Graphics System (Version 2.5.2, Schrödinger, LLC). Results The consensus α-neurotoxins can be successfully expressed in K. phaffii Successful expression of the consensus toxins in K. phaffii was confirmed, checking for a close replication of the structural attributes of native α-neurotoxins purified from snake venoms. The genes responsible for encoding the SCC and LCC consensus toxins were cloned into the pPICZα A expression vector. A secretion signal sequence was utilized to secrete the toxins into the culture media. To assess the success of the expression and purification process, SDS-PAGE and MALDI-TOF output were used, confirming the expected size of the toxins and successful purification. The SDS-PAGE analysis was performed under reducing and non-reducing conditions to verify the successful formation of disulfide bonds in the consensus toxins. A shift in the migration pattern on the gel was observed when treated with the reducing agent DTT, suggesting the presence of disulfide bonds. The consensus toxins α-neurotoxins resemble native structure The secondary structure of the consensus toxins SCC and LCC was evaluated using CD spectroscopy (Figure 1C). This analysis showed that the secondary structure of the SCC closely resembled that of the native α-neurotoxins from snake venom, specifically α- cobratoxin and short neurotoxin 1. However, the low concentration of the LCC hindered the reliability of the CD spectra, hence no definitive conclusions were drawn about its secondary structural similarity to native toxins. Effective nanobody selection from immunized camelid libraries Prior to selection, the successful biotinylation of both LCC and SCC consensus toxins was confirmed through mass spectrometry analysis, showing one biotin molecule per toxin. Phage display selection was performed using mixed nanobody libraries derived from two immunized llamas. Two separate selection campaigns were carried out; one with two rounds of selection using LCC as the antigen (TPL1158), and the other with three rounds of selection using SCC as the antigen (TPL1163). The enrichment of the rounds was evaluated using a polyclonal phage ELISA. Identification of potential nanobody candidates Following the selection rounds, the nanobody-encoding genes from both campaigns were isolated and subcloned into a bacterial expression vector for further characterization. A total of 186 clones from each selection campaign were randomly chosen for evaluation using a DELFIA. Biotinylated SCC or LCC was used to determine if the nanobodies could recognize and bind to the respective consensus toxins. The output of this screening process was then narrowed down through subsequent screens and characterization, leading to the identification of the top clones. The progression from the initial pool of clones to the final selected clones was achieved as the selection criteria became more stringent through various screens and characterization steps. The nanobodies that demonstrated a positive signal in the primary screening were selected for further analysis. A total of 88 clones from TPL1158 and 76 clones from TPL1163, all exhibiting binding against their respective consensus toxin with a signal higher than 10 times the background, underwent a second DELFIA screening. During this screening, the clones were assessed for their binding affinity to various biotinylated native toxins. Clones from TPL1158 were tested against the LC-α-neurotoxin α-cobratoxin (N. kaouthia), venom fractions containing primary LC-α-neurotoxins (fraction 8 from N. nivea (Nn8) and fraction 4 from D. viridis (Dv4)), and short neurotoxin 1 (N. pallida). TPL1163 clones were tested against short neurotoxin 1 (N. pallida), venom fractions enriched with primary SC-α- neurotoxins (fraction 4 from N. nivea (Nn4), fraction 4 from D. polylepis (Dp4), and fraction 1 from D. viridis (Dv1)), and the LC-α-neurotoxin α-cobratoxin (N. kaouthia). Additionally, the binding of the nanobodies to Eu-Streptavidin alone was evaluated in samples without added toxins. The majority of the tested nanobodies showed the capability to bind to a diverse range of native α-neurotoxins purified from venom produced by different snake species, suggesting their cross-binding ability. Clones from TPL1158 were also evaluated for their binding affinity to SC-α-neurotoxins, whereas clones from TPL1163 were tested for their recognition of LC-α- neurotoxins. As expected, TPL1158 clones showed no binding to LC-α-neurotoxins, and TPL1163 clones showed no binding to SC-α-neurotoxins. Signals comparable to the background were detected in the negative control, suggesting that the observed signals are due to nanobody binding to the toxins, not to non-specific binding to streptavidin. Selection of unique nanobody clones After the second DELFIA screen, a subset of 61 clones from TPL1158 and 34 clones from TPL1163, all demonstrating cross-binding to native toxins, were chosen for DNA sequencing. The sequencing aimed to ensure diversity, with unique sequences selected from groups of clones with similar DELFIA signals. As a result, 26 unique clones from TPL1158 and 9 unique clones from TPL1163 were identified and the antibody framework and complementarity determining regions (CDRs) of the clones were annotated and analyzed. A subset of these clones was selected for further characterization due to the limitations of conducting extensive BLI and DELFIA experiments. Ultimately, 21 clones from TPL1158 and 7 clones from TPL1163 were selected for further analysis. The selected nanobodies bind to several different α-neurotoxin toxins with high affinity To investigate the binding capability of the selected nanobody clones from TPL1158 and TPL1163, BLI analysis was employed against a panel of native α-neurotoxins. Specifically, the screening was performed against three LC-α-neurotoxins (α-cobratoxin, Dv4, and Nn8) and three SC-α-neurotoxins (short neurotoxin 1, Dv1, and Dp4). After the initial BLI screening, the clones that exhibited the most promising binding curves with a fast on-rate and slow off-rate were selected. In total five clones from TPL1158 and four clones from TPL1163 were further assessed in kinetics experiments. All of these clones showed high binding affinity towards the tested toxins, with dissociation constant (KD) values ranging from 200 nM to below 1 pM, mostly in the low nanomolar to picomolar range. The observed low KDvalues for most of the clones can be attributed to the exceptionally slow off-rates below 1.0·10-7s-1measured during the kinetics experiments, highlighting the strong and stable interactions between the nanobodies and the respective toxins, see Figures 1 and 2. Figure 1 shows the BLI binding curves from TPL1158. The measured binding curves of the nanobodies from the TPL1158 selection against three different LC-α-neurotoxins including their fitted curves. Figure 2 shows the BLI binding curves from TPL1163. The measured binding curves of the nanobodies from the TPL1163 selection against three different short α- neurotoxins including their fitted curves. No binding was observed for TPL1163_01_C11, 01_G05, and 02_A01 to Dp4. Notably, clone TPL1158_01_A11 behaves differently compared to the other four nanobodies targeting LC-α-neurotoxins. This nanobody possesses high affinity and a slow off-rate specifically towards Dv4. In contrast, the KDs towards α-cobratoxin and Nn8 is approximately 100 and 1000 times higher, respectively. This could indicate that this nanobody is able to differentiate between α-neurotoxin originating from different elapid genera. The selected nanobodies bind to a range of α-neurotoxins from different snake species To evaluate the binding capabilities of the nanobodies and their recognition of various α- neurotoxins, a comprehensive DELFIA assay was conducted, covering multiple toxin fractions. The nanobodies from TPL1158, specific to LC-α-neurotoxins, were tested against six different LC-α-neurotoxins, while the nanobodies from TPL1163, targeting SC-α-neurotoxins, were tested against seven different SC-α-neurotoxins. Additionally, all nanobodies were examined for their binding affinity towards a cytotoxic 3FTx. A sequence alignment and percentage identity of the tested toxins was determined to provide insights into the similarities and differences between the consensus toxins and the toxins used in this experiment. The results indicated that the TPL1158 nanobodies exhibited binding to most of the tested LC-α-neurotoxins, with C04, C09, and C06 also showing slight affinity towards α- Bungarotoxin, the LC-α-neurotoxin with the least sequence similarity to LCC among the tested LC-α-neurotoxins. Remarkably, the TPL1158_01_A11 nanobody exhibited binding signals exclusively with venom fractions from D. viridis, while no signals were observed to any of the tested toxins derived from cobra species. This observation is consistent with the kinetic data obtained through BLI. Among the TPL1163 nanobodies, TPL1163_01_H08 demonstrated a relatively limited recognition of toxins compared to the other three SC-α-neurotoxin binders. However, the remaining three nanobodies (C11, G05, and A01) exhibited a broad recognition of various SC-α-neurotoxins. These three nanobodies not only demonstrated recognition and binding to a diverse range of SC-α-neurotoxins but also exhibited binding to the tested cytotoxin. This finding suggests that these nanobodies possess a broader binding capability beyond their specificity for α-neurotoxins. The nanobodies show neutralization in vitro The neutralisation of toxicity by the nanobodies was assessed using two distinct methods. First, a DELFIA-based assay was utilised to evaluate the inhibition of toxin binding to the nicotinic acetylcholine receptor (nAChR), which is the natural target of long-chain α- neurotoxins (Figure 3). Second, the ability to protect nAChR function was measured using patch-clamp electrophysiology (Figure 4). In the DELFIA-based assay, clones TPL1158_01_C04, TPL1158_01_C09, and TPL1158_02_C06 showed disruption of the interaction between all the tested long-chain α- neurotoxins and the nAChR. TPL1158_01_A11 and TPL1158_01_B05, however, only showed significant signs of disruption for fraction Dv4 and fractions Dv4 and Dp7 respectively. At a 1:1 molar ratio, the binding of both Dv4 and Dp7 to the nAChR was completely disrupted. A higher molar excess was required to achieve complete disruption for Dv6, α-cobratoxin, and α-bungarotoxin (Figure 3). In the electrophysiology experiment, the effectiveness of various α-neurotoxins in functionally inhibiting the nAChR response was first determined. Subsequently, the α- neurotoxins were preincubated with the nanobodies at different molar ratios to evaluate the nanobodies’ ability to neutralize the current-inhibiting activity of these α-neurotoxins. As a negative control, no toxin was added to the nanobodies. All the clones exhibited broad neutralization capabilities, with TPL1158_01_C04 and TPL1158_01_C09 showing the ability to neutralize all tested LC-α-neurotoxins. The molar ratios necessary to inhibit the toxic activity for each of the toxins was comparable in both nanobodies, suggesting a similar mechanism for binding and neutralisation. Dv4 toxicity was drastically reduced even in a molar deficit of nanobody (1:3 nanobody:toxin), Dv6 and Dp7 were neutralised in a 1:1 ratio while the complete neutralisation of α-cobratoxin and α-bungarotoxin necessitated a molar excess of nanobody (3:1 and 9:1 respectively).TPL1158_01_A11 only neutralized toxins originating from mambas, consistent with the data obtained from BLI and DELFIA (Figure 4). Conversely, none of the nanobodies targeting SC-α-neurotoxins were able to neutralize Nn4 (Figure 4), which closely resembles Nm3 used in the cross-binding DELFIA, where these nanobodies also displayed low binding affinity. Selected nanobodies show neutralization in vivo Neutralisation experiments were performed to evaluate the ability of two selected nanobodies; TPL1158_01_C04 and TPL1158_01_C09, to prevent death of mice when preincubated with 3 LD50s of α-cobratoxin (Figure 5). After injection with the toxin preincubated with TPL1158_01_C09, no evident signs of envenomation appeared over the 24 hour observation period, demonstrating complete in vivo neutralisation. Conversely, mice injected with the toxin preincubated with TPL1158_01_C04 showed severe signs of envenomation and died approximately 2 hours after injection. These signs of envenomation included weakness, paralysis of limbs, and eventual respiratory distress and death. Nonetheless, this represents an extension of time of death compared with the control (toxin preincubated with PBS only), where mice died within the first 10 minutes after injection. Broad neutralisation of selected nanobodies is A structural and mechanistic explanation for the cross-reactivity of TPL1158_01_C09 was provided from X-ray crystallography and simulations. The crystal structure of TPL1158_01_C09 in complex with α-cobratoxin was determined at 2.8 Å resolution refined to R / Rfree value of 0.28 / 0.2981. The structural analysis of the binding interface reveals that most direct atomic interactions, including hydrophobic or hydrogen bonds and salt bridges, are formed through the CDR-H3 loop of the nanobody (VHH). The longest loop of α- cobratoxin, which connects the second and third β-strand of the β-sheet core, primarily governs antigen recognition. This interaction is further supported by residues in the CDR-H1 and CDR-H2 loops, as well as P7 from the third β-strand of α-cobratoxin (Figure 6). Key interactions involved in stabilizing the complex are between VHH-D27 and α-cobratoxin-R36, as well as VHH-D100G and α-cobratoxin-R33. Additionally, the binding interface is further formed by a hydrogen bond network involving VHH-W99 and α-cobratoxin-P7, as well as VHH- S100B and α-cobratoxin-K35. This network is further supported by hydrogen bond interactions of VHH-Y100 with VHH-D27 and α-cobratoxin-R36. The binding pose in the crystal structure of TPL1158_01_C09 in complex with α-cobratoxin mimics the binding interface of neurotoxins with the nicotinic acetylcholine receptor, as both the nanobody and the receptor interact with similar toxin residues (data not shown). To characterise the binding interface of TPL1158_01_C09 with additional toxins, the available X-ray structure (this disclosure) was used as template to model the VHH-toxin complexes (α- cobratoxin, α-neurotoxin from D. polylepis, LCC and α-bungarotoxin). To assess critical contacts, the interactions in the interface found in the X-ray structure (Figure 6A) were initially calculated. Based on the MD simulations of the modelled complexes, hydrogen bond and salt bridge interactions were calculated, revealing similar binding poses and interactions of TPL1158_01_C09 with the four different toxins. While in general the epitope is very conserved, the biggest difference in the paratope footprint can be found for α-bungarotoxin. In particular, one key arginine residue at position 39 that is involved in both salt bridge and hydrogen bond interactions in all other complexes is missing in α-bungarotoxin. This results in an increased variability of the TPL1158_01_C09 - α-bungarotoxin complex, which is also reflected in a slightly shifted paratope interaction footprint (Figure 6B). Additionally, a higher number of aromatic and hydrophobic contacts were found in the consensus toxin complex compared to complexes with α-neurotoxin, α-cobratoxin and α-bungarotoxin, as it has a higher number of tryptophan residues in the antigen binding site. Conclusion The inventors of the present application successfully expressed consensus α-neurotoxins using a yeast expression system based on the host K. phaffii. These consensus toxins were designed to mimic the structural features of native snake α-neurotoxins while presenting a well-defined antigenic target. Building on the knowledge that consensus toxins can be used as immunogens to generate polyclonal antibodies capable of neutralizing venom from different snake species, the inventors focused on leveraging this concept for the discovery of monoclonal nanobodies using phage display technology. The use of consensus toxins as antigens in our phage display campaigns offered several advantages. The primary benefit was their utility as antigens for the discovery of cross- reactive nanobodies with broad neutralization capabilities compared to nanobodies and antibodies discovered using traditional cross-panning methods. In the cross-panning method, the level of antigen variability that the library may encounter during successive panning rounds is restricted to only a few targets. On the other hand, consensus proteins are deliberately designed to present the features of multiple targets, thereby substantially broadening the possibilities for discovering cross-reactive binding proteins. Even though the cross-panning strategy has previously been shown to be useful for discovering broadly neutralizing antibodies against other toxins, the antigens exchanged in the successive panning rounds have often shared a high degree of sequence identity and function in these prior studies. When this is not the case, the antigen exchange leads to a decrease in the amount of phages displaying antibodies capable of binding to multiple targets. The capability of the consensus toxins to select antibodies that are able to bind multiple toxins is evident from the data presented here. In particular, the ability of the discovered nanobodies to cross- bind α-neurotoxins from snake species beyond those native to Africa indicates the potential for these nanobodies to target venom toxins from diverse geographical regions and snake genera. By mimicking multiple similar antigens, it thus seems that the use of consensus proteins may enable a potentially more facile discovery approach for monoclonal antibodies and nanobodies with broadly neutralizing capacities. In relation to snakebite envenoming, this may help make recombinant antivenom products simpler to formulate, at they can be comprised of fewer antibodies, as well as it may enable the development of even more polyvalent recombinant antivenoms that cover snake species from vaster geographic regions. In this relation, we note that an exceptional broad recognition of toxins was seen in this study, with the discovery of nanobodies capable of binding cytotoxic 3FTx toxins that share down to 43% sequence identity to SCC. Observations like these further emphasize the potential of using consensus toxins to select antibodies with very broad specificity. To assess the neutralization capacities of the discovered nanobodies, functional neutralization assays were conducted using automated patch-clamping. Notably, all the tested clones showed broad neutralization capacities against LC-α-neurotoxins, with two particular clones, TPL1158_01_C04 and TPL1158_01_C09, demonstrating the ability to neutralize all tested LC- α-neurotoxins. Furthermore, the nanobodies targeting LC-α-neurotoxins exhibited similar IC50 values to an affinity-matured IgG previously discovered in our group, which had performed exceptionally well in vivo. This observation highlights the potency of these nanobodies, especially in the light of them being monovalent and therefore not benefitting from a potential avidity effect unlike the bivalent IgGs. Surprisingly, it also shows that the broad cross-reactivity observed for these nanobodies does not seem to compromise affinity or potency. 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Claims

CLAIMS 1. A monoclonal binding agent comprising complementarity determining regions CDR1, CDR2, and CDR3 of a single domain antibody (sdAb), said monoclonal binding agent being able to bind and / or block and / or neutralise Elapidae three-finger toxins (3FTx) of multiple snake species, wherein the monoclonal binding agent is selected from an antibody, an antibody format, an antibody fragment or an antibody analogue.

2. The monoclonal binding agent according to claim 1, which binds the consensus Elapidae α- neurotoxin amino acid sequence SEQ ID NO: 1 or 2.

3. The monoclonal binding agent according to claim 1 or 2, wherein the CDR1, CDR2, and CDR3 each comprises or consists of an amino acid sequence determined according to either Kabat, Chothia, IMTG or Aho numbering schemes and present in an amino acid sequence selected from any one of SEQ ID NOs: 3-11, optionally wherein the CDR1 contain 1, 2, or 3 amino acid substitutions and / or the CDR2 contain 1, 2, or 3 amino acid substitutions and / or the CDR3 contains 1, 2, or 3 amino acid substitutions, wherein substitutions preferably are conservative.

4. The monoclonal binding agent according to any one of claims 1-3, wherein the three-finger toxins (3FTx) are neurotoxins or cytotoxins.

5. The monoclonal binding agent according to any one of claims 1-4, which is able to bind, block and / or neutralise Elapidae neurotoxins, preferably α-neurotoxins of multiple snake species.

6. The monoclonal binding agent according to claim 5, wherein the α-neurotoxins are short- chain α-neurotoxins (SC), long-chain α-neurotoxins (LC), non-conventional α-neurotoxins (NC) or atypical α-neurotoxins of multiple snake species, preferably, wherein the α- neurotoxins are short-chain α-neurotoxins (SC) or long-chain α-neurotoxins (LC) of multiple snake species.

7. The monoclonal binding agent according to claim 6, wherein the short-chain α-neurotoxins (SC) or long-chain α-neurotoxins (LC) are selected from the list comprising Short neurotoxin 1, Short neurotoxin 2, Short neurotoxin 3, Short neurotoxin 4, Short neurotoxin 5, Short neurotoxin 6, Short neurotoxin A, Short neurotoxin B, Short neurotoxin C, Short neurotoxin D, Cobrotoxin-b, α-elapitoxin-Nn2a, α-neurotoxin NTX-1, α-elapitoxin-Dpp2C, α-elapitoxin- Oh3a, Long neurotoxin 1, Long neurotoxin 2, Long neurotoxin 3, Long neurotoxin 4, α- elapitoxin-Dv2b, α-elapitoxin-Dpp2b, α-cobratoxin and α-bungarotoxin.

8. The monoclonal binding agent according to any one of claims 1-7, wherein the CDR1, CDR2 and CDR3 have the amino acid sequences: a) SEQ ID NOs: 12, 13, 14, or b) SEQ ID NOs: 15, 16, 17, or c) SEQ ID NOs: 18, 19, 20, or d) SEQ ID NOs: 21, 22, 23, or e) SEQ ID NOs: 24, 25, 26, or f) SEQ ID NOs: 27, 2829 or g) SEQ ID NOs: 30, 31, 32 or h) SEQ ID NOs: 33, 34, 35 or i) SEQ ID NOs: 36, 37, 38, wherein CDR1 optionally contains 1, 2, or 3 amino acid substitutions and / or CDR2 optionally contains 1, 2, or 3 amino acid substitutions and / or CDR3 optionally contains 1, 2, or 3 amino acid substitutions, preferably 1, 2, or 3 conservative substitutions.

9. The monoclonal binding agent according to any one of claims 1-8, which is able to bind, block and / or neutralize short-chain-α-neurotoxins (SC) of multiple snake species, which comprises binding regions CDR1, CDR2, and CDR3 having the respective SEQ ID Nos: 12, 13, 14, or 15, 16, 17 or 18, 19, 20, or 21, 22, 23, wherein each CDR is determined according to Aho numbering scheme, optionally wherein CDR1 contain 1, 2, or 3 amino acid substitutions, CDR2 contain 1, 2, or 3 amino acid substitutions and CDR3 contain 1, 2, or 3 amino acid substitutions.

10. The monoclonal binding agent according to any one of claims 1-8, which is able to bind, block and / or neutralize long-chain-α-neurotoxins (LC) of multiple snake species, which comprises binding regions CDR1, CDR2, and CDR3 having the respective SEQ ID Nos: 24, 25, 26, or 27, 28, 29, or 30, 31, 32, or 33, 34, 35, or 36, 37, 38,wherein each CDR is determined according to Aho numbering scheme, optionally wherein CDR1 contain 1, 2, or 3 amino acid substitutions, CDR2 contain 1, 2, or 3 amino acid substitutions and CDR3 contain 1, 2, or 3 amino acid substitutions.

11. The monoclonal binding agent according to claim 10, wherein the binding regions CDR1, CDR2, and CDR3 have the respective SEQ ID Nos: 33, 34, and 35, optionally wherein CDR1 contains 1, 2, or 3 amino acid substitutions, CDR2 contains 1, 2, or 3 amino acid substitutions and CDR3 contains 1, 2, or 3 amino acid substitutions.

12. The monoclonal binding agent according to claim 11, which comprises aspartic acid (D) or glutamic acid (E) in position 27 of CDR1, preferably D, and which further comprises an aromatic amino acid residue selected from tryptophan (W), tyrosine (Y) and phenylalanine (F) in position 99 of CDR3, preferably W, and which further comprises an aromatic amino acid residue selected from W, Y and F in position 100 of CDR3, preferably Y.

13. The monoclonal binding agent according to claim 11 or 12, which is able to bind to α- cobratoxin.

14. The monoclonal binding agent according to any one of claims 1-7, comprising an amino acid sequence selected from any one of SEQ ID NOs: 3-11, wherein each CDR is determined according to the Aho numbering scheme, and optionally wherein the CDR1 contains 1, 2, or 3 amino acid substitutions and / or the CDR2 contains 1, 2, or 3 amino acid substitutions and / or the CDR3 contains 1, 2, or 3 amino acid substitutions, and wherein the same amino acid sequence selected from any one of SEQ ID NOs: 3-11 comprises framework regions FR1, FR2, FR3, and FR4, wherein each FR is determined according to the Aho numbering scheme, optionally wherein the FR1 contains 1, 2, 3, 4 or 5 amino acid substitutions and / or the FR2 contains 1, 2, 3, 4 or 5 amino acid substitutions and / or the FR3 contains 1, 2, 3, 4 or 5 amino acid substitutions and / or the FR4 contains 1, 2, 3, 4 or 5 amino acid substitutions, wherein substitutions preferably are conservative.

15. The monoclonal binding agent according to claim 14, comprising the amino acid sequence with SEQ ID NO: 10, optionally wherein the CDR1 contains 1, 2, or 3 amino acid substitutions and / or the CDR2 contains 1, 2, or 3 amino acid substitutions and / or the CDR3 contains 1, 2, or 3 amino acid substitutions, and optionally wherein the FR1 contains 1, 2, 3, 4 or 5 amino acid substitutions and / or the FR2 contains 1, 2, 3, 4 or 5 amino acid substitutions and / or the FR3 contains 1, 2, 3, 4 or 5 amino acid substitutions and / or the FR4 contains 1, 2, 3, 4 or 5 amino acid substitutions, wherein substitutions preferably are conservative.

16. The monoclonal binding agent according to claim 15, consisting of the amino acid sequence with SEQ ID NO:

10.

17. The monoclonal binding agent according to any one of claims 1-15, wherein the CDR1, CDR2, and CDR3 are comprised in an antibody format selected from the group consisting of IgA-like antibody formats, IgE-like antibody formats, IgG-like antibody formats, and IgM-like antibody formats, preferably human, an IgY-like antibody format, and an sdAb, an sdAb- sdAb, an sdAb-Fc fusion, multimers of sdAbs, multimers of sdAb-Fc fusions or an effective binding fragment thereof.

18. The monoclonal binding agent according to any one of claims 1-15 or 17, wherein the fragment or analogue of an antibody is selected from an Fab, an Fab', an F(ab')2, a variable fragment (Fv), a triabody, a tetrabody, a minibody, a bispecific F(ab')2, a trispecific F(ab')2, a diabody, a bispecific diabody, a single chain variable fragment (scFv), an scFv-Fc, an Fab- Fc, a VHH, a bispecific scFv, or a combination thereof, preferably a VHH.

19. The monoclonal binding agent according to claim 17 or 18, further comprising a linker linking the monoclonal binding agent to an antibody format, fragment or analogue of an antibody.

20. A pharmaceutical composition comprising the monoclonal binding agent according to any one of claims 1-19, wherein the composition further comprises a pharmaceutically acceptable carrier and / or vehicle and / or diluent and / or excipient, preferably wherein the composition is formulated for being administered by injection, such as intravenous, sub-cutaneous, or intramuscular injection.

21. The monoclonal binding agent according to any one of claims 1-19, or the pharmaceutical composition according to claim 20, for use as a medicament, preferably for use in the treatment or prevention of snake envenomation.

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