Uses, methods, polypeptides and polynucleotides

Abstract

Polypeptides comprising bacteriophage polypeptides for use in preventing or treating autoimmune diseases, for example type 1 diabetes. Polypeptides comprising fragments or variants of bacteriophage po

Description

The present invention relates to certain polypeptides, polynucleotides and compositions for use in preventing or treating an autoimmune disease, such as type 1 diabetes. The present invention also relates to methods and uses for preventing or treating an autoimmune disease, such as type 1 diabetes. The invention also provides vaccine compositions comprising certain polypeptides or polynucleotides, and also provides isolated polypeptide and isolated polynucleotide products. The invention further provides methods of screening for an autoimmune disease (e.g. type 1 diabetes) that comprise determining the level, in a body fluid sample, of certain biomarkers. Autoimmune diseases are conditions that result from an anomalous (or aberrant) response of a subject’s immune system, wherein it mistakenly targets and attacks healthy, functioning parts of the body as if they were foreign organisms. Thus, autoimmune diseases are characterized by a subject’s aberrant immune response against its own cells / tissues (i.e. an anti-self immune response). Autoimmune diseases can be life-altering for sufferers thereof, and thus there is a clear need for new therapies for the prevention or treatment of autoimmune diseases. One example of an autoimmune disease is type 1 diabetes (T1D). T1D is characterized by the destruction of insulin-producing pancreatic beta cells by the immune system. Thus, T1D is characterized by insulin deficiency. The cause of T1D is not fully characterized, but it is thought to involve genetic and environmental factors. T1D can cause many complications if left untreated (e.g. onset of diabetic ketoacidosis and nonketotic hyperosmolar coma, heart disease, stroke, kidney failure, foot ulcers and damage to the eyes). Typically, for subjects having T1D, insulin therapy is required for survival. Insulin regulates glucose levels in the blood stream. A diabetic diet and exercise are important parts of management. Currently, there is no way known to prevent T1D. There is clearly an urgent need to develop therapies for the prevention or treatment of autoimmune diseases, such as T1D. The identification of agents that could be used as vaccines for the prevention or treatment of autoimmune diseases (e.g. T1D) is thus clearly highly desirable. Surprisingly, the present inventors have found that there are significant differences in the levels (or titres) of serum antibodies that bind to bacteriophage polypeptides of T1D patients as compared to in the serum of healthy control patients. More specifically, they have found that there is a higher level of such antibodies in serum samples from control healthy subjects as compared to in serum samples from T1D patients. It is believed that these antibodies have a protective effect in the healthy control subjects, i.e. protect against autoimmunity being triggered by bacteriophage polypeptides. The inventors’ findings indicate that bacteriophage polypeptides (or fragments or variants thereof) could be used as vaccines to provide a protective effect (immunoprotective effect) against bacteriophage polypeptide-triggered autoimmunity, and thus be useful as vaccines for the prevention or treatment of autoimmune diseases, for example T1D. The finding that there are significant differences in the serum levels (or titres) of antibodies that bind to bacteriophage polypeptides of T1D patients as compared to in the serum of healthy control patients additionally provides the basis for methods of screening for autoimmune diseases, e.g. using such antibodies as biomarkers. Thus, in one aspect the present invention provides a polypeptide for use in preventing or treating an autoimmune disease in a subject, wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Bacteriophage polypeptides are polypeptides encoded by the genome of a bacteriophage. Thus, in accordance with the present invention, the bacteriophage protein of (a) is, or corresponds to, a polypeptide encoded by the genome of a bacteriophage. By “corresponds to” means that the bacteriophage polypeptide of (a) has the same primary amino acid sequence as a wild-type or native or full-length bacteriophage polypeptide. The bacteriophage polypeptide of (a) may be an artificial or synthetic sequence that does not have the same secondary or tertiary structure as the corresponding wild-type or native or full-length bacteriophage polypeptide, or it may be a denatured form of the wild-type bacteriophage polypeptide. In some embodiments, the bacteriophage may be a prophage. A prophage is a bacteriophage genome that is integrated into the circular bacterial chromosome or that exists as an extrachromosomal plasmid within a bacterial cell. In some preferred embodiments, the bacteriophage polypeptide is encoded by a dsDNA (double stranded DNA) bacteriophage. In some embodiments, the bacteriophage is a bacteriophage of the gut microbiota (e.g. of said subject). Thus, in some embodiments the bacteriophage is a bacteriophage of the intestinal microbiome (e.g. of said subject). Thus, in some embodiments, the bacteriophage polypeptide of (a) is, or corresponds to, a bacteriophage polypeptide of a bacteriophage of the gut microbiota (or intestinal microbiome). By “corresponds to” means that the bacteriophage polypeptide of (a) has the same primary amino acid sequence as a wild-type or native or full-length bacteriophage polypeptide of a bacteriophage of the gut microbiota (or intestinal microbiome). In some embodiments, the bacteriophage is a bacteriophage of (or that infects) bacteria of the bacterial phylum Bacillota. In some embodiments, the bacteriophage is a bacteriophage of (or that infects) bacteria of the bacterial class Clostridia. In some embodiments, the bacteriophage is a bacteriophage of (or that infects) bacteria of the bacterial genus Ruminococcus orBlautia. In some embodiments, the bacteriophage is a bacteriophage of (or that infects) the bacterial species Ruminococcus gnavus. In some embodiments, the bacteriophage is a prophage that is integrated into the circular bacterial chromosome or that exists as an extrachromosomal plasmid within a bacteria, preferably said bacteria is of the phylum Bacillota, preferably the class Clostridia, preferably the genus Blautia or Ruminococcus. In some embodiments, the bacteriophage is a bacteriophage capable of infecting a bacterium of the phylum Bacillota, preferably the class Clostridia, preferably the genus Blautia or Ruminococcus. In some embodiments, the bacteriophage is a bacteriophage of the class Caudoviricetes. In some embodiments, the bacteriophage is Caudoviricetes sp. isolate ct9Hq3 (Genbank Accession Nos. BK021288.1 and BK020595.1) or Caudoviricetes sp. isolate ctdVd (Genbank Accession No. BK054880.1). Caudoviricetes sp. isolate ct9Hq3 and / or Caudoviricetes sp. isolate ctdVd, and related or analogous bacteriophage isolates, are examples of bacteriophages that encode in their genome toxins (including holins, e.g. a holin of, or related to or substantially homologous to, SEQ ID NO:1). In some embodiments, the bacteriophage is a bacteriophage of (or that infects) bacteria of the bacterial phylum Proteobacter. In some embodiments, the bacteriophage is a prophage that is integrated into the circular bacterial chromosome or that exists as an extrachromosomal plasmid within a bacteria, preferably said bacteria is of the phylum Proteobacter. In some embodiments, the bacteriophage is a bacteriophage capable of infecting a bacterium of the phylum Proteobacter. In some embodiments, the bacteriophage is Caudoviricetes sp. isolate ct8hD15 (Genbank Accession No.: BK040308.1) or Bacteriophage sp. isolate 2486_27286 (Genbank Accession No. OP074632.1) or Bacteriophage sp. isolate 1253_64355 (Genbank Accession No. OP030915.1) or Bacteriophage sp. isolate 3040_71421 (GenBank Accession No. OP072501.1) or Bacteriophage sp. isolate 1414_73244 (Genbank Accession No. OP030954.1) or Bacteriophage sp. isolate 2142_29128 (Genbank Accession No. OP074359 1). Caudoviricetes sp. isolate ct8hD15, Bacteriophage sp. isolate 2486_27286, Bacteriophage sp. isolate 1253_64355, Bacteriophage sp. isolate 3040_71421, Bacteriophage sp. isolate 1414_73244 and / or Bacteriophage sp. isolate 2142_29128, or related or analogous bacteriophage isolates, are examples of bacteriophages that encode in their genome a polypeptide of SEQ ID NO:2 or that encode polypeptides related to or substantially homologous thereto. In accordance with the present invention, the bacteriophage polypeptide of (a) is an immunogenic polypeptide. In accordance with the present invention, the bacteriophage polypeptide of (a) is typically used to elicit (or induce) an immune response (e.g. an immunoprotective immune response). Thus, in accordance with the present invention, the bacteriophage polypeptide of (a) typically elicits (or induces) an immunoprotective effect. Put another way, when used in accordance with the present invention the bacteriophage polypeptide of (a) is typically used as a vaccine polypeptide to elicit an immune response (i.e. have an immunogenic effect) that protects against the induction of autoimmunity. In preferred embodiments, the bacteriophage polypeptide of (a) is, or corresponds to, a toxin. Such toxins may be toxic to eukaryotic cells (e.g. human cells). In particularly preferred embodiments, the bacteriophage polypeptide of (a) is, or corresponds to, a holin. Holins are a family of toxins. Holins are small proteins produced by (encoded by) dsDNA (double stranded DNA) bacteriophages in order to trigger and control the degradation of the host's cell wall at the end of the lytic cycle. Thus, in some embodiments, the bacteriophage polypeptide has the same primary amino acid sequence as a wild-type or native or full-length bacteriophage polypeptide toxin (preferably a holin). Although it may have an amino acid sequence that corresponds to a wild-type or native or full-length bacteriophage polypeptide toxin (e.g. a holin), in some embodiments the bacteriophage polypeptide of (a) may not (itself) be toxic (e.g. it may be an artificial or synthetic sequence that does not have the same secondary or tertiary structure as the corresponding wild-type or native or full-length bacteriophage polypeptide toxin (e.g. holin), or it may be a denatured form of the wild-type bacteriophage polypeptide toxin (e.g. holin)). In some embodiments, the bacteriophage polypeptide of (a) has the amino acid sequence of SEQ ID NO:1. SEQ ID NO:1 sets forth the amino acid sequence of a holin of a bacteriophage of bacteria of the genus Blautia. In some embodiments, the bacteriophage polypeptide of (a) has the amino acid sequence of SEQ ID NO:2. SEQ ID NO:2 sets forth the amino acid sequence of a Proteobacter bacteriophage polypeptide. As described above, in some embodiments, the polypeptide for use in accordance with the invention comprises a bacteriophage polypeptide that is, or that corresponds to, a full-length (or wild-type or native) bacteriophage polypeptide. However, in preferred embodiments, a fragment of a bacteriophage polypeptide is used. Thus, in a preferred aspect, the present invention provides a polypeptide for use in preventing or treating an autoimmune disease in a subject, wherein said polypeptide comprises a fragment (or portion) of a bacteriophage polypeptide, or a variant thereof. Fragments, by definition, do not include the corresponding full-length (or wild-type or native) polypeptide. The term "fragment" as used herein refers to fragments of biological relevance, e.g. fragments capable of inducing an immunogenic response (e.g. an immunoprotective response or a vaccine effect) when administered to a subject. In some embodiments, a fragment of a bacteriophage polypeptide (or a variant thereof) may be at least 5, at least 6, at least 7, at least 8, at least 9, at least 10, at least 15, at least 20, at least 30, at least 40, at least 50, at least 75, at least 100, at least 250, at least 500 or at least 1000 amino acids in length. In some embodiments, a fragment of a bacteriophage polypeptide (or a variant thereof) may be, for example, up to 10, up to 12, up to 15, up to 20, up to 30, up to 40, up to 50, up to 60, up to 70, up to 80, up to 90, up to 100, up to 250, up to 500, or up to 1000 amino acids in length. In some embodiments, a fragment of a bacteriophage polypeptide (or a variant thereof) may be, for example, 5 to 10, 5 to 12, 5 to 15, 5 to 20, 5 to 30, 5 to 40, 5 to 50, 5 to 60, 5 to 70, 5 to 80, 5 to 90, 5 to 100, 5 to 250, 5 to 500 or 5 to 1000 amino acids in length. In some embodiments, a fragment of a bacteriophage polypeptide (or a variant thereof) may be, for example, 10 to 15, 10 to 20, 10 to 30, 10 to 40, 10 to 50, 10 to 60, 10 to 70, 10 to 80, 10 to 90, 10 to 100, 10 to 250, 10 to 500 or 10 to 1000 amino acids in length. In some embodiments, a fragment of a bacteriophage polypeptide (or a variant thereof) may be, for example, 20 to 30, 20 to 40, 20 to 50, 20 to 60, 20 to 70, 20 to 80, 20 to 90, 20 to 100, 20 to 250, 20 to 500 or 20 to 1000 amino acids in length. In some embodiments, a fragment of a bacteriophage polypeptide or a variant thereof) may be, for example, 50 to 100, 50 to 250, 50 to 500 or 50 to 1000 amino acids in length. In preferred embodiments, a fragment of a bacteriophage polypeptide or a variant thereof) is 10 to 30 amino acids in length, preferably 15 to 25 amino acids in length. In a preferred embodiment, a fragment of a bacteriophage polypeptide is 20 amino acids in length. As is evident from the discussion elsewhere herein, in some preferred embodiments the fragment is a fragment of a bacteriophage toxin, for example a fragment of a holin. In some embodiments, the fragment is a fragment of the amino acid sequence set forth in SEQ ID NO:1 (or a fragment of a variant of SEQ ID NO:1). Suitable fragment lengths are discussed elsewhere herein. For example, in some embodiments, a fragment of the amino acid sequence set forth in SEQ ID NO:1 (or a variant thereof) may be at least 5, at least 10, at least 15, at least 20, at least 50 or at least 75 amino acids in length. In some embodiments, a fragment of the amino acid sequence set forth in SEQ ID NO:1 (or a variant thereof) may be up to 10, up to 20, up to 50, up to 90 or up to 98 amino acids in length. In some embodiments, a fragment of the amino acid sequence set forth in SEQ ID NO:1 (or a variant thereof) may be 5 to 10, 5 to 20, 5 to 50, 5 to 90 or 5 to 98 amino acids in length. In some embodiments, a fragment of the amino acid sequence set forth in SEQ ID NO:1 (or a variant thereof) may be 10 to 20, 10 to 50, 10 to 90 or 10 to 98 amino acids in length. In some embodiments, a fragment of the amino acid sequence set forth in SEQ ID NO:1 (or a variant thereof) may be 20 to 50, 20 to 90 or 20 to 98 amino acids in length. In some embodiments, the fragment is a fragment of the amino acid sequence set forth in SEQ ID NO:2 (or a fragment of a variant of SEQ ID NO:2). Suitable fragment lengths are discussed elsewhere herein. For example, in some embodiments, a fragment of the amino acid sequence set forth in SEQ ID NO:2 (or a variant thereof) may be at least 5, at least 10, at least 15 or at least 20 amino acids in length. In some embodiments, a fragment of the amino acid sequence set forth in SEQ ID NO:2 (or a variant thereof) may be up to 10, up to 20, up to 30 or up to 31 amino acids in length. In some embodiments, a fragment of the amino acid sequence set forth in SEQ ID NO:2 (or a variant thereof) may be 5 to 10, 5 to 20, 5 to 30 or 5 to 31 amino acids in length. In some embodiments, a fragment of the amino acid sequence set forth in SEQ ID NO:2 (or a variant thereof) may be 10 to 20, 10 to 30 or 10 to 31 amino acids in length. In some embodiments, a fragment of the amino acid sequence set forth in SEQ ID NO:2 (or a variant thereof) may be 20 to 30 or 20 to 31 amino acids in length. In a particularly preferred embodiment, the fragment has (or comprises or consists of) the amino acid sequence of SEQ ID NO: 3. In another embodiment, the fragment has (or comprises or consists of) an amino acid sequence that is a variant of (or substantially homologous to) the amino acid sequence of SEQ ID NO:3. In another particularly preferred embodiment, the fragment has (or comprises or consists of) the amino acid sequence of SEQ ID NO: 4. In another embodiment, the fragment has (or comprises or consists of) an amino acid sequence that is a variant of (or substantially homologous to) the amino acid sequence of SEQ ID NO:4. Thus, in one aspect, the invention provides a polypeptide for use in preventing or treating an autoimmune disease (e.g. T1D) in a subject, wherein said polypeptide comprises (or consists of) a fragment of the bacteriophage polypeptide of SEQ ID NO:1 or SEQ ID NO:2, or a fragment of a variant of SEQ ID NO:1 or SEQ ID NO:2. In such embodiments, said polypeptide does not comprise or consist of the amino acid sequence of SEQ ID NO:1 or SEQ ID NO:2 (i.e. does not consist of the full-length SEQ ID NO:1 or full-length SEQ ID NO:2 sequence). Thus, in a preferred aspect, the invention provides a polypeptide for use in preventing or treating an autoimmune disease (e.g. T1D) in a subject, wherein said polypeptide comprises (or consists of) the amino acid sequence of SEQ ID NO:3 or SEQ ID NO:4, or a variant of SEQ ID NO:3 or SEQ ID NO:4. In some such embodiments, said polypeptide does not comprise or consist of the amino acid sequence of SEQ ID NO:1 or SEQ ID NO:2 (i.e. does not consist of the full-length SEQ ID NO:1 or full-length SEQ ID NO:2 sequence). In some embodiments of the present invention, a variant of a bacteriophage polypeptide in accordance with the invention is used, or a variant of a fragment in accordance with the invention is used. A variant may have a sequence that is “substantially homologous” to a given amino acid sequence (e.g. to a given bacteriophage polypeptide or given fragment). A “substantially homologous” (or variant) sequence may be a sequence containing 1, 2, 3, 4, 5 or 6 (preferably 1, 2 or 3, preferably 1 or 2, more preferably 1) amino acid substitutions or deletions or additions compared to the given amino acid sequence (e.g. compared to a given bacteriophage polypeptide sequence or given fragment sequence), or a sequence having at least 70% sequence identity to the given amino acid sequence. Amino acid sequences that are “substantially homologous” to a given sequence (e.g. a given bacteriophage polypeptide sequence or a given fragment sequence) include sequences having, or sequences comprising (or consisting of) a sequence that has, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, or at least 99% sequence identity to the given sequence. Sequence identities of at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% are preferred. Alterations in the amino acid sequences in variants (substantially homologous sequences) can be with conservative or non-conservative amino acids. Preferably said alterations are conservative amino acid substitutions. A "conservative amino acid substitution", as used herein, is one in which the amino acid residue is replaced with another amino acid residue having a similar side chain. Families of amino acid residues having similar side chains have been defined in the art, including basic side chains (e.g. lysine, arginine, histidine), acidic side chains (e.g. aspartic acid, glutamic acid), uncharged polar side chains (e.g. asparagine, glutamine, serine, threonine, tyrosine, cysteine), nonpolar side chains (e.g. glycine, cysteine, alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan), beta-branched side chains (e.g. threonine, valine, isoleucine) and aromatic side chains (e.g. tyrosine, phenylalanine, tryptophan, histidine). The terms “variant” and "substantially homologous" also include modifications or chemical equivalents of the amino acid sequences of the present invention that perform substantially the same function as the bacteriophage polypeptides or fragments of the invention in substantially the same way. In one embodiment, a variant of a bacteriophage polypeptide is a variant of (i.e. a sequence substantially homologous to) the amino acid sequence set forth in SEQ ID NO:1. The substantially homologous sequence may be as described above. In some embodiments, a variant of SEQ ID NO:1 contains 1,2, 3, 4 or 5 (preferably 1, 2 or 3, preferably 1 or 2, more preferably 1) amino acid substitutions or deletions or additions compared to SEQ ID NO:1. In some embodiments, a variant of SEQ ID NO:1 has at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, or at least 99% sequence identity to SEQ ID NO:1. In one embodiment, a variant of a bacteriophage polypeptide is a variant of (i.e. a sequence substantially homologous to) the amino acid sequence set forth in SEQ ID NO:2. The substantially homologous sequence may be as described above. In some embodiments, a variant of SEQ ID NO:2 contains 1, 2, 3, 4 or 5 (preferably 1, 2 or 3, preferably 1 or 2, more preferably 1) amino acid substitutions or deletions or additions compared to SEQ ID NO:2. In some embodiments, a variant of SEQ ID NO:2 has at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, or at least 99% sequence identity to SEQ ID NO:2. In one embodiment, a variant is a variant of (i.e. a sequence substantially homologous to) the amino acid sequence set forth in SEQ ID NO:3. The substantially homologous sequence may be as described above. In some embodiments, a variant of SEQ ID NO:3 contains 1, 2, 3, 4 or 5 (preferably 1, 2 or 3, preferably 1 or 2, more preferably 1) amino acid substitutions or deletions or additions compared to SEQ ID NO:3. In some embodiments, a variant of SEQ ID NO:3 has at least 75%, at least 80%, at least 85%, at least 90% or at least 95% sequence identity to SEQ ID NO:3. In one embodiment, a variant is a variant of (i.e. a sequence substantially homologous to) the amino acid sequence set forth in SEQ ID NO:4. The substantially homologous sequence may be has described above. In some embodiments, a variant of SEQ ID NO:4 contains 1, 2, 3, 4 or 5 (preferably 1, 2 or 3, preferably 1 or 2, more preferably 1) amino acid substitutions or deletions or additions compared to SEQ ID NO:4. In some embodiments, a variant of SEQ ID NO:4 has at least 75%, at least 80%, at least 85%, at least 90% or at least 95% sequence identity to SEQ ID NO:4. Any substantially homologous sequences or variants should typically have the ability to induce an immunogenic response (e.g. an immunoprotective response or a vaccine effect) when administered to a subject. Methods of carrying out the above described manipulation of amino acids (e.g. to generate “substantially homologous” or “variant” sequences) are well known to a person skilled in the art. Homology (e.g. sequence identity) may be assessed by any convenient method. However, for determining the degree of homology (e.g. identity) between sequences, computer programs that make multiple alignments of sequences are useful, for instance Clustal W (Thompson, Higgins, Gibson, Nucleic Acids Res., 22:4673-4680, 1994). If desired, the Clustal W algorithm can be used together with BLOSUM 62 scoring matrix (Henikoff and Henikoff, Proc. Natl. Acad. Sci. USA, 89:10915-10919, 1992) and a gap opening penalty of 10 and gap extension penalty of 0.1, so that the highest order match is obtained between two sequences wherein at least 50% of the total length of one of the sequences is involved in the alignment. Other methods that may be used to align sequences are the alignment method of Needleman and Wunsch (Needleman and Wunsch, J. Mol. Biol., 48:443, 1970) as revised by Smith and Waterman (Smith and Waterman, Adv. Appl. Math., 2:482, 1981) so that the highest order match is obtained between the two sequences and the number of identical amino acids is determined between the two sequences. Other methods to calculate the percentage identity between two amino acid sequences are generally art recognized and include, for example, those described by Carillo and Lipton (Carillo and Lipton, SIAM J. Applied Math., 48:1073, 1988) and those described in Computational Molecular Biology, Lesk, e.d. Oxford University Press, New York, 1988, Biocomputing: Informatics and Genomics Projects. Generally, computer programs will be employed for such calculations. Programs that compare and align pairs of sequences, like ALIGN (Myers and Miller, CABIOS, 4:11-17, 1988), FASTA (Pearson and Lipman, Proc. Natl. Acad. Sci. USA, 85:2444-2448, 1988; Pearson, Methods in Enzymology, 183:63-98, 1990) and gapped BLAST (Altschul et al., Nucleic Acids Res., 25:3389-3402, 1997), BLASTP, BLASTN, or GCG (Devereux, Haeberli, Smithies, Nucleic Acids Res., 12:387, 1984) are also useful for this purpose. Furthermore, the Dali server at the European Bioinformatics institute offers structure-based alignments of protein sequences (Holm, Trends in Biochemical Sciences, 20:478-480, 1995; Holm, J. Mol. Biol., 233:123-38, 1993; Holm, Nucleic Acid Res., 26:316-9, 1998). By way of providing a reference point, sequences according to the present invention having 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% homology, sequence identity etc. may be determined using the ALIGN program with default parameters (for instance available on Internet at the GENESTREAM network server, IGH, Montpellier, France). In some embodiments, the bacteriophage polypeptide, fragment or variant is one for which the level (or titre), in a body fluid sample obtained from one or more subjects having an autoimmune disease (e.g. a group or population of subjects having an autoimmune disease), of an antibody that binds (e.g. specifically binds) to said bacteriophage polypeptide, fragment or variant is lower (e.g. significantly lower) than a control level of an (e.g. said) antibody that binds to said bacteriophage polypeptide, fragment or variant. Control levels are discussed elsewhere herein. Typically and preferably, said control level is a level that has been determined in the same sample type obtained from one or more subjects (e.g. a group or population of subjects) that do not have an autoimmune disease (e.g. healthy or normal subjects). In some embodiments, the bacteriophage polypeptide, fragment or variant for use in (or suitable for use in) preventing or treating T1D is one for which the level (or titre), in a body fluid sample obtained from one or more subjects having T1D (e.g. a group or population of subjects having T1D), of an antibody that binds (e.g. specifically binds) to said bacteriophage polypeptide, fragment or variant is lower (e.g. significantly lower) than a control level of an (e.g. said) antibody that binds to said bacteriophage polypeptide, fragment or variant. Typically and preferably, said control level is a level that has been determined in the same sample type obtained from one or more subjects (e.g. a group or population of subjects) that do not have T1D (e.g. healthy or normal subjects). The "lower" (or decreased or reduced) level in comparison to a control level as described herein includes any measurable decrease or reduction of the antibody level when compared with a control level. Preferably, the level is significantly lower (or decreased or reduced) compared to the level found in an appropriate control (e.g. control sample or subject or population). More preferably, the significantly lower (or decreased) levels are statistically significant, preferably with a p-value of <0.05. In some embodiments, a lower (or decreased level) may be a decrease in level of 2?2%, 2? 3%, 2? 5%, 2? 10%, 2? 25%, 2? 50%, 2^75%, 2?80%, 2?90%, ^95% or ^99% compared to the level found in an appropriate control sample or subject or population (i.e. when compared to a control level). “Control levels” are discussed elsewhere herein. A “control level” may be the level in a control subject or population (e.g. in a sample(s) that has been obtained from a control subject or population). A “control level” may be a level of an antibody that binds (e.g. specifically binds) to said bacteriophage polypeptide, fragment or variant where the control level is derived from (or established based on or calculated from) the level in a control subject or population (e.g. in a sample(s) that has been obtained from a control subject or population). Such a population also may be referred to as a reference population. Appropriate control subjects (or populations) or samples would be readily identified by a person skilled in the art (and are discussed elsewhere herein), and preferably are healthy (or normal) subjects. The control level may correspond to the level of an antibody that binds to said bacteriophage polypeptide, fragment or variant in appropriate control subjects or samples or populations, e.g. may correspond to a cut-off or threshold level or range found in a control or reference population. Control levels may also be referred to as "reference" levels. The control level may be a discrete figure or a range. Identifying (or screening for) bacteriophage polypeptides, fragments or variants for which there is a level (or titre), in a body fluid sample, of an antibody that is lower (e.g. significantly lower) than a control level of an antibody would be routine for a person skilled in the art. For example, bacteriophage polypeptides, fragments or variants to be tested (or screened) could be immobilized on a solid support (e.g. a microarray or ELISA plate, or similar) and contacted, in parallel experiments, with body fluid samples from subjects having an autoimmune disease (e.g. T1D) and from control (e.g. healthy) subjects, and antibody binding to the bacteriophage polypeptides, fragments or variants can be assessed and quantified and compared between the two groups. Antibody titre (or level) may thus be determined or measured or quantified (or be as determined or measured or quantified) in a binding assay (e.g. an immunoassay, such as a microarray or a ELISA assay) in which the antibody (or a sample containing the antibody) is contacted with a bacteriophage polypeptide, fragment or variant in question and the (amount of) binding of the antibody to said bacteriophage polypeptide, fragment or variant is determined or measured or quantified, thereby determining the titre (or level) of the antibody. Typically, a secondary antibody (with a detectable (e.g. fluorescent) label attached thereto) may be used as a means to measure (or detect or quantify) antibody binding. References herein to “body fluid” and “body fluid samples” include any body fluids or body fluid samples. A preferred type of body fluid and body fluid sample is a blood sample. A preferred type of blood sample is serum. Thus, serum is a particularly preferred body fluid or body fluid sample in accordance with the present invention. Body fluids and body fluid samples are also discussed elsewhere herein. As set out elsewhere herein, the present invention provides a polypeptide for use in preventing or treating an autoimmune disease (e.g. T1D) in a subject, wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). In some embodiments, the present invention provides a polypeptide for use in preventing or treating an autoimmune disease (e.g. T1D) in a subject, wherein said polypeptide consists of (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). In some embodiments, polypeptides for use in accordance with the present invention may comprise additional (non-bacteriophage polypeptide-derived) amino acid sequences (i.e. in addition to bacteriophage polypeptide, fragment, or variant sequences), for example amino acid sequences that act as tags (e.g. affinity tags) or other useful moieties. In some preferred embodiments, the polypeptide for use in accordance with the invention comprises (or consists of) a fragment of a bacteriophage polypeptide (or a variant thereof). Thus, in some embodiments the polypeptide for use in accordance with the invention does not comprise (or consist of) a full-length (or native or wild-type) bacteriophage polypeptide sequence (or any other wild-type sequence). Thus, in some embodiments the polypeptide for use in accordance with the invention does not comprise the amino acid sequence of SEQ ID NO:1 or SEQ ID NO:2. In some preferred embodiments, the polypeptide for use in accordance with the invention comprises (or consists of) the amino acid sequence of a fragment of a bacteriophage polypeptide (or a variant thereof), but does not comprise any other amino acid sequences derived from a (e.g. said) bacteriophage polypeptide. Thus, in some such embodiments, the only amino acid sequence derived from (or based on) a bacteriophage polypeptide sequence is an amino acid sequence of a fragment of a bacteriophage polypeptide (or a variant thereof). Polypeptides for use in accordance with the present invention may comprise additional (non-bacteriophage polypeptidederived) amino acid sequences (e.g. in addition to a fragment of a bacteriophage polypeptide), for example amino acid sequences that act as tags (e.g. affinity tags) or other useful moieties. In some preferred embodiments, the polypeptide for use in accordance with the invention comprises (or consists of) the amino acid sequence of a fragment of SEQ ID NO:1 (or a variant thereof), but does not comprise any other amino acid sequences derived from (or based on) SEQ ID NO:1. Thus, in some such embodiments, the only amino acid sequence derived from (or based on) a bacteriophage polypeptide sequence is an amino acid sequence of a fragment of SEQ ID NO:1 (or a variant thereof). Polypeptides for use in accordance with the present invention may comprise additional (non-bacteriophage polypeptide derived) amino acid sequences (i.e. in addition to a fragment of SEQ ID NO:1), for example amino acid sequences that act as tags (e.g. affinity tags) or other useful moieties. In some preferred embodiments, the polypeptide for use in accordance with the invention comprises (or consists of) the amino acid sequence of a fragment of SEQ ID NO:2 (or a variant thereof), but does not comprise any other amino acid sequences derived from SEQ ID NO:2. Thus, in some such embodiments, the only amino acid sequence derived from (or based on) a bacteriophage polypeptide sequence is an amino acid sequence of a fragment of SEQ ID NO:2 (or a variant thereof). Polypeptides for use in accordance with the present invention may comprise additional (non-bacteriophage polypeptide derived) amino acid sequences (i.e. in addition to a fragment of SEQ ID NO:2), for example amino acid sequences that act as tags (e.g. affinity tags) or other useful moieties. In some preferred embodiments, the polypeptide for use in accordance with the invention comprises (or consists of) the amino acid sequence of SEQ ID NO:3 (or a variant thereof), but does not comprise any other amino acid sequences derived from SEQ ID NO:1. Thus, in some such embodiments, the only amino acid sequence derived from (or based on) a bacteriophage polypeptide sequence is the amino acid sequence of SEQ ID NO:3 (or a variant thereof). Polypeptides for use in accordance with the present invention may comprise additional (non-bacteriophage polypeptide derived) amino acid sequences (i.e. in addition to SEQ ID NO:3), for example amino acid sequences that act as tags (e.g. affinity tags) or other useful moieties. In some preferred embodiments, the polypeptide for use in accordance with the invention comprises (or consists of) amino acid sequence of SEQ ID NO:4 (or a variant thereof), but does not comprise any other amino acid sequences derived from SEQ ID NO:2. In some such embodiments, the only amino acid sequence derived from (or based on) a bacteriophage polypeptide sequence is the amino acid sequence of SEQ ID NO:4 (or a variant thereof). Polypeptides for use in accordance with the present invention may comprise additional (non-bacteriophage polypeptide derived) amino acid sequences (i.e. in addition to SEQ ID NO:4), for example amino acid sequences that act as tags (e.g. affinity tags) or other useful moieties. Polypeptides for use in accordance with the present invention are typically immunogenic polypeptides. In accordance with the present invention, polypeptides are typically used to elicit (or induce) an immunoprotective effect. Put another way, when used in accordance with the present invention polypeptides may be vaccine polypeptides that elicit an immune response (i.e. have an immunogenic effect) that protects against the induction of autoimmunity. The efficacy of the uses of polypeptides (or polynucleotides or compositions) in accordance with the invention may be tested (e.g. by ELISA) by establishing the presence or absence of antibodies (preferably neutralising antibodies) against the polypeptide in the subject’s blood. Methods for doing this are routine in the art and well within the competence of the skilled person. The use of the term “polypeptide” herein does not imply any limitations regarding the length of (number of amino acids in) the molecule (polypeptide). Thus, the use of the term “polypeptide” does not imply that the molecule (polypeptide) must have a particular minimum length or maximum length. Thus, amino acid chains that might be referred to as “peptides” or “oligopeptides” are included within the meaning of the term “polypeptide” as used herein. As explained above, the polypeptides for use in accordance with the invention may comprise (or consist of) a fragment of a bacteriophage polypeptide. As explained above, the minimum length of a “fragment” may be 5 amino acids in length. Accordingly, the polypeptides of use in the present invention may be at least 5 amino acids in length (but they are typically longer, e.g. having a length as described elsewhere herein). In another aspect, the present invention provides a polynucleotide encoding a polypeptide as defined elsewhere herein for use in preventing or treating an autoimmune disease in a subject. Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants, subjects, etc.). Alternatively viewed, in one aspect, the present invention provides a polynucleotide for use in preventing or treating an autoimmune disease in a subject, wherein said polynucleotide encodes a polypeptide, said polypeptide comprising (or consisting of) (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants, subjects, etc.). Alternatively viewed, in one aspect, the present invention provides a nucleic acid molecule for use in preventing or treating an autoimmune disease in a subject, wherein said nucleic acid molecule comprises a nucleotide sequence that encodes a polypeptide, said polypeptide comprising (or consisting of) (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants, subjects, etc.). Alternatively viewed, in one aspect, the present invention provides a nucleic acid molecule for use in preventing or treating an autoimmune disease in a subject, wherein said nucleic acid molecule encodes a polypeptide, said polypeptide comprising (or consisting of) (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants, subjects, etc.). In preferred embodiments, polynucleotides (or nucleic acid molecules) for use in accordance with the present invention are polynucleotides for use in preventing or treating T1D. In some embodiments, the polynucleotide or nucleic acid molecule in accordance with the invention is a DNA. In some embodiments, the polynucleotide or nucleic acid molecule in accordance with the invention is a RNA. In some embodiments, the nucleic acid molecule in accordance with the invention is a synthetic nucleic acid analogue (or a polynucleotide analogue). As used herein, the term "nucleic acid molecule" or "polynucleotide" refers to a single- or double-stranded polynucleotide containing deoxyribonucleotides or ribonucleotides that are linked by 3 '-5' phosphodiester bonds, as well as polynucleotide (or nucleic acid) analogues. A nucleic acid molecule (or polynucleotide) includes, but is not limited to, DNA, RNA, and cDNA. A polynucleotide analogue (or nucleic acid analogue) may possess a backbone other than a standard phosphodiester linkage found in natural polynucleotides and, optionally, a modified sugar moiety or moieties other than ribose or deoxyribose. Polynucleotide analogues (or nucleic acid analogues) contain bases capable of hydrogen bonding by Watson-Crick base pairing to standard polynucleotide bases, where the analogue backbone presents the bases in a manner to permit such hydrogen bonding in a sequencespecific fashion between a nucleotide analogue molecule and bases in a standard polynucleotide. Examples of synthetic nucleic acid analogues (or polynucleotide analogues) include, but are not limited to xeno nucleic acid (XNA), bridged nucleic acid (BNA), glycol nucleic acid (GNA), peptide nucleic acids (PNAs), yPNAs, morpholino polynucleotides, locked nucleic acids (LNAs), threose nucleic acid (TNA), 2'-0-Methyl polynucleotides, 2'-0-alkyl ribosyl substituted polynucleotides, phosphorothioate polynucleotides, and boronophosphate polynucleotides. A polynucleotide (or nucleic acid) analogue may possess purine or pyrimidine analogs, including for example, 7-deaza purine analogues, 8-halopurine analogues, 5-halopyrimidine analogues, or universal base analogues that can pair with any base, including hypoxanthine, nitroazoles, isocarbostyril analogues, azole carboxamides, and aromatic triazole analogues, or base analogues with additional functionality, such as a biotin moiety for affinity binding. In some embodiments, one or more nucleotides of a polynucleotide or nucleic acid molecule may be replaced with corresponding nucleotide analogues. Different nucleotide analogues can be used to achieve the desired base pairing properties. Those include, among others, peptide nucleic acid (PNA), Morpholino, glycol nucleic acid (GNA), threose nucleic acid (TNA), xeno nucleic acid (XNA) and locked nucleic acid (LNA). Preferably, the polynucleotide (or nucleic acid molecule) is a messenger RNA (mRNA) molecule. An mRNA molecule for use in accordance with the present invention may be used as an mRNA vaccine. The skilled person is familiar with mRNA vaccines, and features thereof, and would be readily able to prepare mRNA vaccines in accordance with the present invention. A detailed review of mRNA vaccines, and features thereof, is provided by Pardi et al., Nature Reviews Drug Discovery, Vol.17, pages 261-279. The mRNA molecule may be, for example, an in vitro transcribed (IVT) mRNA (e.g. produced from a linear DNA template using for example a T7, a T3 or an Sp6 phage RNA polymerase). The resulting mRNA molecule product may comprise, for example an open reading frame that encodes the bacteriophage polypeptide or fragment or variant of interest, flanking UTRs, a 5' cap and a poly(A) tail. Such mRNAs are thus typically engineered to resemble fully processed mature mRNA molecules. Compositions, vehicles and systems for delivering polynucleotide (e.g. mRNA) vaccines to subjects are also well known in the art (e.g. they are discussed in Pardi et al., supra). The skilled person is also familiar with other nucleic acid molecule (e.g. DNA) based vaccines, and compositions, vehicles and delivery systems for the same. In another aspect, the present invention provides a molecule that encodes a polypeptide for use in preventing or treating an autoimmune disease (e.g. T1D) in a subject, said polypeptide comprising (or consisting of) (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants, subjects, etc.). In another aspect, the present invention provides a molecule that encodes genetic information that can be translated into a polypeptide in a living cell or artificial system, for use in preventing or treating an autoimmune disease (e.g. T1D) in a subject, said polypeptide comprising (or consisting of) (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Such molecules include DNA, RNA (e.g. mRNA) and synthetic nucleic acid analogues. Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants, subjects, etc.). In some aspects and embodiments of the present invention, polypeptides, polynucleotides for use in accordance with the invention are present in (or formulated in) compositions (e.g. pharmaceutical, immunogenic, or vaccine compositions), said composition comprising a polypeptide or polynucleotide of use in accordance with the present invention and one or more other component, e.g. one or more diluents, excipients, carriers and / or adjuvants. Such compositions are described elsewhere herein. In accordance with the present invention, any autoimmune disease may be prevented or treated. A preferred autoimmune disease in accordance with the present invention is Type 1 diabetes. Type 1 diabetes is also referred to herein as “T1D”. Thus, in a preferred aspect, the present invention provides a polypeptide for use in preventing or treating Type 1 diabetes in a subject, wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants, subjects, etc.). As used herein, the term "preventing" includes preventing or delaying the onset (or induction or initiation or development) of an autoimmune disease (e.g. T1D) in a subject. Thus, "preventing" encompasses vaccination. The term "treatment" or "therapy" includes any treatment or therapy which results in an improvement in the health or condition of a patient, or of a symptom of an autoimmune disease. "Treatment" is not limited to curative therapies (e.g. those which result in the elimination of an autoimmune disease from a patient), but includes any therapy which has a beneficial effect on the autoimmune disease or the patient, for example, increased overall survival, extension or prolongation of life or remission, induction of remission, a slow-down or reduction of disease progression or the rate of disease progression, subjective improvement in quality of life, reduction in other symptoms related to the disease. Thus, as used herein 'treatment' may refer to reducing, alleviating, ameliorating or eliminating an autoimmune disease, or one or more symptoms thereof, which is being treated, relative to the autoimmune disease or symptom prior to the treatment. Treatment is treatment of a subject, i.e. a subject in need thereof. Each of the prevention and treatment methods and uses can comprise the step of administering to a subject an effective amount, such as a prophylactically or therapeutically effective amount, of a polypeptide in accordance with the invention, a polynucleotide in accordance with the invention, or a composition (e.g. a vaccine composition) in accordance with the invention. A “subject” in accordance with the present invention may be any type of subject capable of suffering from an autoimmune disease (e.g. T1D). Thus, the methods and uses of the invention as described herein can be carried out on any type of subject which is capable of suffering from an autoimmune disease (e.g. T1D). Typically and preferably, the subject is a mammal, for example a human, primate (e.g. monkeys), laboratory mammal (e.g. mice, rats, rabbits, guinea pigs), livestock mammal (e.g. horses, cattle, sheep, pigs) or domestic pet (e.g. cats, dogs). Preferably the subject is a human. In some embodiments, the subject (e.g. a human) is a subject at risk of developing an autoimmune disease (e.g. T1D) or at risk of the occurrence of an autoimmune disease (e.g. T1D). In some embodiments, the subject is a healthy subject or a subject not displaying any symptoms of an autoimmune disease (e.g. T1D). In some other embodiments the subject is a subject having, or suspected of having (or developing), or potentially having (or developing) an autoimmune disease (e.g.TID). In some embodiments of the preventative uses and methods in accordance with the invention, the subject (e.g. a human subject) is a subject that does not have an autoimmune disease (e.g. has not been diagnosed with an autoimmune disease). In some embodiments of the preventative uses and methods in accordance with the invention, the subject (e.g. a human subject) may be a healthy (or normal) subject or a subject or a subject not displaying any symptoms of an autoimmune disease (e.g. T1D). In some embodiments of the preventative uses and methods in accordance with the invention, the subject (e.g. a human subject) is a subject at risk of developing an autoimmune disease (e.g. T1D) or at risk of the occurrence of an autoimmune disease (e.g. T1D). In some embodiments of the uses and methods for treating an autoimmune disease in accordance with the invention, the subject (e.g. a human subject) is a subject that has an autoimmune disease (e.g. has been diagnosed with an autoimmune disease). In some embodiments, uses and methods of the invention may further comprise an initial step of selecting a subject (e.g. a human subject) at risk of developing an autoimmune disease (e.g. T1D) or at risk of the occurrence of an autoimmune disease (e.g. T1D), or having or suspected of having (or developing) an autoimmune disease (e.g. T1D), or potentially having (or developing) an autoimmune disease (e.g. T1D). In another aspect, the present invention provides an isolated polypeptide, said isolated polypeptide comprising (or consisting of) (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants). In some embodiments, the isolated polypeptide comprises (or consists of) the amino acid sequence of SEQ ID NO:1 or a fragment or variant thereof, or comprises (or consists of) the amino acid sequence of SEQ ID NO:2 or a fragment or variant thereof. In some embodiments, the isolated polypeptide comprises (or consists of) a fragment of the amino acid sequence of SEQ ID NO:1 or a variant thereof, or comprises a fragment of the amino acid sequence of SEQ ID NO:2 or a variant thereof. Fragments and variants are described elsewhere herein in connection with other aspects of the invention and that description may be applied mutatis mutandis here. In some embodiments, the isolated polypeptide isolated polypeptide does not comprise (or consist of) the amino acid sequence of SEQ ID NO:1 or SEQ ID NO:2, or any other wild-type sequence. In some embodiments, the amino acid sequence of the isolated polypeptide of the invention contains at least one modification (e.g. insertion, deletion or substitution) relative the amino acid sequence given in SEQ ID NO:1 or SEQ ID NO:2. In some embodiments, the isolated polypeptide comprises (or consists of) the amino acid sequence of SEQ ID NO:3 or SEQ ID NO:4, or a sequence substantially homologous thereto (i.e. or a variant sequence). Substantially homologous (variant) sequences are described elsewhere herein and that description may be applied, mutatis mutandis, here. In some embodiments, the isolated polypeptide comprises (or consists of) the amino acid sequence of SEQ ID NO:3 or SEQ ID NO:4, or a sequence substantially homologous thereto, wherein said substantially homologous sequence is a sequence containing 1, 2, 3, 4 or 5 amino acid substitutions or deletions or additions compared to the given amino acid sequence, or wherein said substantially homologous sequence is a sequence that has at least 80% sequence identity to the given sequence. In some embodiments, the isolated polypeptide comprises the amino acid sequence of SEQ ID NO:3. In some embodiments, the isolated polypeptide comprises the amino acid sequence of SEQ ID NO:4. In some embodiments, the isolated polypeptide consists of the amino acid sequence of SEQ ID NO:3. In some embodiments, the isolated polypeptide consists of the amino acid sequence of SEQ ID NO:4. Preferably, isolated polypeptide products of the invention do not comprise (or consist of) the amino acid sequence of SEQ ID NO:1 or SEQ ID NO:2 (or any other full-length or wild-type protein sequence). Methods for synthesising polypeptides are well known in the art. A common technique used for preparing linear polypeptides is Fmoc SPPS (Solid Phase Peptide Synthesis). In SPPS, small porous beads are treated with functional linkers on which polypeptide chains can be built using repeated cycles of wash-coupling-wash. The synthesized polypeptide is then released from the beads using chemical cleavage. Other methods for synthesising polypeptides include using other chemical synthesis procedures, in vitro translation, or by introducing a suitable expression vector encoding a polypeptide of interest into cells. In another aspect, the present invention provides an isolated polynucleotide encoding a polypeptide as defined elsewhere herein Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants). Thus, in one aspect, the present invention provides an isolated polynucleotide that encodes a polypeptide, said polypeptide comprising (or consisting of) (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants, isolated polypeptides, etc.). Alternatively viewed, in one aspect, the present invention provides an isolated nucleic acid molecule, wherein said nucleic acid molecule comprises a nucleotide sequence that encodes a polypeptide, said polypeptide comprising (or consisting of) (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants, isolated polypeptides, etc.). Alternatively viewed, in one aspect, the present invention provides an isolated nucleic acid molecule that encodes a polypeptide, said polypeptide comprising (or consisting of) (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants, isolated polypeptides, etc.). Polynucleotides (or nucleic acid molecules) of (or for use in accordance with) the present invention may be deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) and may include naturally occurring bases including adenine, guanine, cytosine, thymidine and uracil. They may also contain modified bases. Polynucleotides (or nucleic acid molecules) may be double stranded or single stranded. The nucleic acid molecules may be wholly or partially synthetic or recombinant. Methods of producing (or synthesizing) polynucleotides (or nucleic acid molecules) are well-known in the art. In some embodiments, the polynucleotide (or nucleic acid molecule) is a messenger RNA (mRNA) molecule. The mRNA molecule may be suitable for use as an mRNA vaccine polynucleotide. The mRNA molecule may be, for example, an in vitro transcribed (IVT) mRNA (e.g. produced from a linear DNA template using for example a T7, a T3 or an Sp6 phage RNA polymerase). The mRNA molecule may comprise, for example an open reading frame that encodes the bacteriophage polypeptide or fragment or variant of interest, flanking UTRs, a 5' cap and a poly(A) tail. Polynucleotides (or nucleic acid molecules) of (or for use in accordance with) the present invention may synthetic nucleic acid molecules, for example as discussed elsewhere herein. In another aspect, the present invention provides a molecule that encodes a polypeptide, said polypeptide comprising (or consisting of) (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants, subjects, etc.). In another aspect, the present invention provides a molecule that encodes genetic information that can be translated into a polypeptide in a living cell or artificial system, said polypeptide comprising (or consisting of) (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Such molecules include DNA, RNA (e.g. mRNA) and synthetic nucleic acid molecules. Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants, subjects, etc.). The polypeptides and polynucleotides (or nucleic acid molecules) of the invention are generally "isolated" or "purified" molecules insofar as they are distinguished from any such components that may be present in situ within a human or animal body or a tissue sample derived from a human or animal body. The sequences may, however, correspond to or be substantially homologous to sequences as found in a human or animal body. Thus, the term "isolated" or "purified" as used herein in reference to polypeptides and polynucleotides, refers to such molecules when isolated from, purified from, or substantially free of their natural environment (if indeed they occur naturally), or refers to such molecules when produced by a technical process, i.e. includes recombinant and synthetically produced molecules. Thus, when used in connection with a polypeptide or polynucleotide of the invention, the term "isolated" or "purified" typically refers to a polypeptide or polynucleotide substantially free of cellular material or other proteins from the source from which it is derived. In some embodiments, particularly where the polypeptide or polynucleotide is to be administered to humans or animals, such isolated or purified polypeptides or polynucleotides are substantially free of culture medium when produced by recombinant techniques, or chemical precursors or other chemicals when chemically synthesized. The invention also provides a vector or plasmid comprising a polynucleotide (or nucleic acid molecule) of the invention. Preferably, the vector is an expression vector. The vector and / or plasmid may comprise one or more regulatory sequences which are operably linked to the sequence which encodes a polypeptide in accordance with the invention, e.g. one or more enhancer, promoter and / or transcriptional terminator sequences. A yet further aspect of the invention provides a host cell (e.g. an isolated host cell) comprising one or more vectors or plasmids of the invention. Also provided are host cells comprising one or more of the polynucleotides (or nucleic acid molecules) of the invention. A host cell (e.g. a mammalian host cell, such as human cell) expressing an polypeptide in accordance with the invention forms a yet further aspect. In another aspect, the present invention provides a composition (or formulation) comprising a polypeptide (e.g. an isolated polypeptide) ora polynucleotide (e.g. an isolated polynucleotide) or a nucleic acid molecule (e.g. an isolated nucleic acid molecule) of the invention. Such compositions may further comprise (e.g. be in admixture with) a suitable diluent, carrier, excipient, preservative and / or adjuvant (e.g. a pharmaceutically acceptable diluent, carrier, excipient, preservative and / or adjuvant). Suitable diluent, carrier, excipient, preservative and adjuvants are known to the skilled person in this technical field. The adjuvant is typically an immunologic adjuvant or vaccine adjuvant. Adjuvants are discussed elsewhere herein. Thus, in one aspect the present invention provides a composition comprising a polypeptide or polynucleotide or nucleic acid molecule of the invention, and optionally an acceptable (e.g. a pharmaceutically acceptable) diluent, buffer, preservative, excipient and / or adjuvant. Alternatively viewed, in one aspect the present invention provides a composition comprising a polypeptide (e.g. isolated polypeptide) or a polynucleotide or nucleic acid molecule (e.g. isolated polynucleotide or nucleic acid molecule) encoding said polypeptide, wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants, etc.). Compositions in accordance with the present invention may be for pharmaceutical use, and thus compositions of the invention are preferably pharmaceutically acceptable. In some embodiments, the composition may be an immunogenic composition or a vaccine composition, as described elsewhere herein. The compositions according to the invention may be presented, for example, in a form suitable for oral, nasal, parenteral, intraperitoneal, intravenous, intramuscular, topical or rectal administration. In some embodiments, a form suitable for parenteral administration is preferred. The polypeptides or polynucleotides or nucleic acid molecules defined herein may be presented in the conventional pharmacological forms of administration, such as tablets, coated tablets, nasal sprays, solutions, emulsions, liposomes, powders or capsules. Conventional pharmaceutical excipients as well as the usual methods of production may be employed for the preparation of these forms. Injection solutions may, for example, be produced in the conventional manner, such as by the addition of preservation agents, such as p-hydroxybenzoates, or stabilizers, such as EDTA. The solutions may then be filled into injection vials or ampoules. Nasal sprays may be formulated similarly in aqueous solution and packed into spray containers, either with an aerosol propellant or provided with means for manual compression. Polypeptides or polynucleotides (or nucleic acid molecules) may be formulated in a lipid nanoparticle. Thus, in some embodiments, the composition comprises a polypeptide or a polynucleotide (or a nucleic acid molecule) of the invention encapsulated in a lipid nanoparticle. Polynucleotides (e.g. mRNA) or nucleic acid molecules are particularly preferably formulated in a lipid nanoparticle. Thus, in some embodiments, the composition comprises an mRNA in accordance with the invention encapsulated in a lipid nanoparticle. The pharmaceutical compositions (formulations) of the present invention are preferably administered parenterally. Parenteral administration may be performed by subcutaneous, intramuscular or intravenous injection by means of a syringe. Alternatively, parenteral administration can be performed by means of an infusion pump. A further option is a composition which may be a powder or a liquid for the administration of the antibody in the form of a nasal or pulmonal spray. As a still further option, the polypeptides or polynucleotides or nucleic acid molecules of the invention can also be administered transdermally, e.g. from a patch, optionally an iontophoretic patch, or transmucosally, e.g. bucally. Suitable dosage units can be determined by a person skilled in the art. The pharmaceutical compositions may additionally comprise further active ingredients in the context of co-administration regimens or combined regimens. Preferably, the composition of the invention is an immunogenic composition. As used herein, the term “immunogenic” is intended to refer to the ability to elicit a specific immune response against a (or a given) bacteriophage polypeptide or fragment or variant in accordance with the invention. This response may, for example, be when a composition of the invention is administered to a subject at an appropriate dose and in an appropriate formulation which may include a suitable adjuvant. Adjuvants are discussed elsewhere herein. In particular, the immunogenic composition of the invention is typically capable of inducing antibodies (preferably neutralising antibodies) in a subject against a (or a given) bacteriophage protein or fragment or variant. The capability of a composition of the invention to induce antibodies (e.g. neutralising antibodies) in a subject (e.g. a human subject) may be tested by purifying sera from the blood of subjects to whom the composition has been administered. Antibodies may be measured using ELISA or any other suitable assay. Appropriate assays are known to the skilled person in this technical field. Preferably, the composition (or immunogenic composition) of the invention is a vaccine composition (or vaccine). Thus, in one aspect, the present invention provides a vaccine composition comprising a polypeptide (e.g. isolated polypeptide) or a polynucleotide or nucleic acid molecule (e.g. isolated polynucleotide or nucleic acid molecule) encoding said polypeptide, wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants, etc.). Vaccine compositions may comprise a diluent, excipient and / or carrier. In some embodiments, vaccine compositions in accordance with the present invention further comprise one or more adjuvants. In some embodiments, vaccine compositions are suitable for parenteral administration. As used herein, a vaccine composition (or vaccine) is a composition that may, when administered to an animal subject such as a mammalian subject (e.g. a human subject), stimulate (or elicit) a protective immune response against a particular disease or condition. In accordance with the present invention, a vaccine composition is a composition that may, when administered to an animal subject such as a mammalian subject (e.g. a human subject), stimulate (or elicit) a protective immune response to protect against (e.g. protect against the development of) an autoimmune disease (e.g. T1D). The immune response may be a humoral and / or a cell-mediated immune response. Thus, the vaccine may stimulate B cells and / or T cells. As indicated above, in some embodiments, vaccine compositions in accordance with the present invention may further comprise one or more adjuvants. Suitable adjuvants are known in the art. Examples of suitable adjuvants include those which are selected from the group consisting of: - metal salts such as aluminium hydroxide or aluminium phosphate, - oil in water emulsions, - toll like receptors agonist, (such as toll like receptor 2 agonist, toll like receptor 3 agonist, toll like receptor 4 agonist, toll like receptor 7 agonist, toll like receptor 8 agonist and toll like receptor 9 agonist), - saponins, for example Quil A and its derivatives such as QS7 and / or QS21, - CpG containing oligonucleotides, - 3D -MPL, - (2-deoxy-6-o-[2-deoxy-2-[(R)-3-dodecanoyloxytetra-decanoylamino]-4-o-phosphono-P-D-glucopyranosy]]-2-[(R)-3-hydroxytetradecanoylamino]-a-D-glucopyranosyldihydrogenphosphate), - DP (3S, 9 R) -3-[(R)-dodecanoyloxytetradecanoylamino]-4-oxo-5-aza-9(R)- [(R)-3 -hydroxytetradecanoylamino] decan-1, 10-diol, 1,10-bis(dihydrogenophosphate), and - MP-Ac DP (3S-, 9R) -3-[(R) -dodecanoyloxytetradecanoylamino]-4-oxo-5- aza-9-[(R)-3-hydroxytetradecanoylamino]decan-l, 10-diol, 1-dihydrogenophosphate 10-(6-aminohexanoate), or combinations thereof. In some embodiments, compositions in accordance with the invention (e.g. vaccine compositions) may further comprise a surfactant. Examples of suitable surfactants include Tween (such as Tween 20), Brij and polyethylene glycol. Vaccine preparation is generally described in New Trends and Developments in Vaccines, edited by Voller etal., University Park Press, Baltimore, Maryland, U.S.A., 1978. The amount of the polypeptide or polynucleotide or nucleic acid molecule of the invention present in each vaccine dose may be selected as an amount which induces an immunoprotective response, preferably without significant, adverse, side effects. Such amount may vary depending upon which specific immunogen is employed and / or whether or not the vaccine is adjuvanted. An optimal amount for a particular vaccine can be ascertained by standard studies involving observation of antibody titres and other responses in subjects. Following an initial vaccination, subjects may in some cases receive a subsequent booster (or booster dose). As described above, the present invention provides a polypeptide, or a polynucleotide or nucleic acid molecule encoding said polypeptide, for use in preventing or treating an autoimmune disease in a subject, wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). In another aspect, the present invention provides a composition (e.g. an immunogenic or vaccine composition) for use in preventing or treating an autoimmune disease (e.g. T1D), said composition comprising a polypeptide, or a polynucleotide or nucleic acid molecule encoding said polypeptide, wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects and embodiment of the the invention described herein apply, mutatis mutandis, to this aspect of the invention. In another aspect, the present invention provides (i) a polypeptide, (ii) a polynucleotide or nucleic acid molecule encoding said polypeptide or (iii) a composition comprising said polypeptide or polynucleotide or nucleic acid molecule, for use in vaccinating a subject against an autoimmune disease (e.g. T1D), wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects and embodiment of the the invention described herein apply, mutatis mutandis, to this aspect of the invention. Alternatively viewed, the present invention provides a method of preventing or treating an autoimmune disease (e.g. T1D), said method comprising administering to a subject in need thereof a therapeutically effective amount of (i) a polypeptide, (ii) a polynucleotide or nucleic acid molecule encoding said polypeptide or (iii) a composition comprising said polypeptide or polynucleotide or nucleic acid molecule, wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects and embodiment of the the invention described herein apply, mutatis mutandis, to this aspect of the invention. Alternatively viewed, the present invention provides a method of vaccinating a subject against an autoimmune disease (e.g. T1D), said method comprising administering to a subject in need thereof a therapeutically effective amount of (i) a polypeptide, (ii) a polynucleotide or nucleic acid molecule encoding said polypeptide or (iii) a composition comprising said polypeptide or polynucleotide or nucleic acid molecule, wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects and embodiment of the the invention described herein apply, mutatis mutandis, to this aspect of the invention. A therapeutically effective amount will be determined based on the clinical assessment and can be readily monitored. The present invention also provides the use of (i) a polypeptide, (ii) a polynucleotide or nucleic acid molecule encoding said polypeptide, or (iii) a composition comprising said polypeptide or polynucleotide or nucleic acid molecule, in the manufacture of a medicament for preventing or treating an autoimmune disease, wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects and embodiment of the the invention described herein apply, mutatis mutandis, to this aspect of the invention. The present invention also provides the use of (i) a polypeptide, (ii) a polynucleotide or nucleic acid molecule encoding said polypeptide, or (iii) a composition comprising said polypeptide or polynucleotide or nucleic acid molecule, in the manufacture of a medicament for vaccinating a subject against an autoimmune disease (e.g. T1D), wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects and embodiment of the the invention described herein apply, mutatis mutandis, to this aspect of the invention. In another aspect, the present invention provides the use of (i) a polypeptide, (ii) a polynucleotide or nucleic acid molecule encoding said polypeptide, or (iii) a composition comprising said polypeptide or polynucleotide or nucleic acid molecule, for preventing or treating an autoimmune disease (e.g. T1D), wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects and embodiment of the the invention described herein apply, mutatis mutandis, to this aspect of the invention. In another aspect, the present invention provides the use of (i) a polypeptide, (ii) a polynucleotide or nucleic acid molecule encoding said polypeptide, or (iii) a composition comprising said polypeptide or polynucleotide or nucleic acid molecule for vaccinating a subject against an autoimmune disease (e.g. T1D), wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects and embodiment of the the invention described herein apply, mutatis mutandis, to this aspect of the invention. In another aspect, the present invention provides (i) a polypeptide, (ii) a polynucleotide or nucleic acid molecule encoding said polypeptide, or (iii) a composition comprising said polypeptide or polynucleotide or nucleic acid molecule for use in therapy (or for use in preventing or treating a disease), wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects and embodiment of the the invention described herein apply, mutatis mutandis, to this aspect of the invention. The present invention also provides the use of a (i) polypeptide, (ii) a polynucleotide or nucleic acid molecule encoding said polypeptide, or (iii) a composition comprising said polypeptide or polynucleotide or nucleic acid molecule in the manufacture of a medicament, wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Embodiments of other aspects and embodiment of the the invention described herein apply, mutatis mutandis, to this aspect of the invention. Administration of polypeptides, polynucleotides and compositions to subjects may be by any conventional route. The administration may be by parenteral administration; for example, a subcutaneous or intramuscular injection. Administration may in some embodiments be, for example, by intravenous, subcutaneous, intraperitoneal, or mucosal routes. The invention further includes kits comprising one or more of the isolated polypeptides or isolated polynucleotides or compositions of the invention. Preferably, said kits are for use in the methods and uses as described herein, e.g. the prevention or treatment methods and uses as described herein, or are for use in the screening methods as described herein. Preferably said kits comprise instructions for use of the kit components. Preferably said kits are for preventing or treating autoimmune diseases as described elsewhere herein, and optionally comprise instructions for use of the kit components to prevent or treat such diseases. In another aspect, the present invention provides a method of screening for an autoimmune disease in a subject, said method comprising determining the level, in a body fluid sample, of an antibody that binds to a polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b), wherein said sample has been obtained from said subject. In preferred embodiments of methods of screening in accordance with the present invention, the autoimmune disease is type 1 diabetes (T1D). Screening methods of the present invention include in vitro methods that employ a polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b) in accordance with the invention as a tool (an in vitro tool or reagent) to determine the level, in a body fluid sample, of an antibody that binds to said polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). As described in the Experimental Example section herein, the inventors have found that there are significantly lower levels, in body fluids, of antibodies that bind to bacteriophage-derived polypeptides in subjects having an autoimmune disease (T1D) as compared to in healthy control subjects. Thus, by determining the level of an antibody that binds to a polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b) in accordance with the invention (and e.g. comparing that to a control level), an indication of an autoimmune disease, or autoimmune disease risk or likelihood, can be made (for example an indication of the likelihood of a subject having, or being at risk of developing, an autoimmune disease). Levels (or amounts or titres) of antibodies in a sample can be determined (or measured or quantified) by any appropriate assay, a number of which are well known and documented in the art. Typically, an immunoassay, such as a fluorescence immunoassay, or an ELISA, may be used. In some embodiments, an immunoassay (e.g. a fluorescence immunoassay) is used to determine (or measure or quantify) the amount (or level or titre) of an antibody in a body fluid sample that binds to a polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b). Typically, the polypeptide comprising (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b) in accordance with the invention is contacted with a body fluid sample, and the amount (or level) of antibody binding (e.g. specific antibody binding) to said polypeptide comprising (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b) is determined (or measured or quantified or detected). The polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b) in accordance with the invention may be immobilized on a solid support. Thus, in some embodiments, to determine the level of an antibody in a body fluid sample, the polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b) in accordance with the invention is immobilised on a solid support (e.g. in the well of a microtitre plate or on a microarray), the immobilised polypeptide is contacted with (or incubated with) a body fluid sample under conditions which allow the formation of antibody-antigen (antibody-polypeptide) interactions (or complexes), and the level (or amount) of antibody binding to the immobilised polypeptide is determined (or measured or quantified or detected). This level represents (or corresponds to or reports) the level of an antibody in the body fluid sample. In some embodiments, a secondary antibody which has a detectable label (e.g. a fluorophore) attached thereto may additionally be used, with the secondary antibody being capable of binding to antibodies of (or from) the body fluid sample that have bound to said immobilized polypeptide. Thus, the level (or amount) of antibody from the body fluid sample that has bound to the immobilised polypeptide may be determined by additionally using such a secondary antibody with a detectable label attached thereto. Said secondary antibody would applied to the (or the suspected) immobilized polypeptide-antibody complexes, and the signal from the detectable label determined (or measured or quantified). If the body fluid sample is a human body fluid sample, the secondary antibody is typically an anti-human secondary antibody. The detectable label (e.g. fluorophore) may be used to determine (or measure or quantify) the level (or amount or titre) of the antibody in the sample. In some embodiments, the immobilization of the polypeptide on a solid support is by (or via) a biotin-streptavidin interaction. In some such embodiments, the peptide is biotinylated and the surface of the solid support contains (e.g. is coated with) streptavidin. In some embodiments, the level (or amount) of antibody binding to the immobilised polypeptide is determined (or measured or quantified) by spectrometric means (e.g. spectrophotometric means). Thus, in some embodiments, the level of signal produced by the detectable label on a secondary antibody is is determined (or measured or quantified) by spectrometric means (e.g. spectrophotometric means). In some embodiments of methods of screening of the present invention (e.g. in some embodiments of screening methods based on determining antibody levels), the body fluid sample is a blood sample. A preferred type of blood sample is serum. Thus serum is a particularly preferred body fluid or body fluid sample in accordance with the present invention. In some embodiments of methods of screening of the present invention (e.g. in some embodiments of screening methods based on determining (or detecting) the presence and / or level of a bacteriophage or a bacteriophage polynucleotide or a bacteriophage polypeptide in a sample), the body fluid sample is a faecal sample (or stool sample). The term "sample" also encompasses any material derived by processing a body fluid sample (e.g. derived by processing a blood (e.g. serum) sample). Thus, the term “sample” includes a processed sample (e.g. a processed blood (e.g. serum) sample). Processing of biological samples to obtain a test sample may involve one or more of: filtration, distillation, centrifugation, fractionation, concentration, dilution, purification, inactivation of interfering components, addition of reagents, derivatization, complexation and the like. Suitable processing steps can be selected depending on the features of the method being performed. Any suitable method for isolating body fluid samples (e.g. blood samples or serum samples or faecal samples) may be employed. In some embodiments, methods of screening of the present invention may include a step of processing a sample. In some embodiments, methods of the invention may thus be performed on such processed samples or materials derived from such processed samples. In some embodiments, methods of the invention may thus be performed on samples that have been processed Processing steps include, but are not limited to, isolating (or removing) cells from the sample, isolating (or removing) cell components from the sample. A processing step may involve one or more of filtration, distillation, centrifugation, concentration, dilution, purification, inactivation of interfering components, addition of reagents, derivatization, and the like. Samples can be used immediately or can be stored for later use (e.g. at -80°C). A “subject” in accordance with methods of screening of the present invention may be any type of subject capable of suffering from an autoimmune disease. The description of “subjects” elsewhere herein in relation to other aspects of the invention may be applied, mutatis mutandis, to methods of screening of the present invention. Preferably, the subject is a human subject. In some embodiments of methods of screening of the present invention, the subject is a subject at risk of developing an autoimmune disease, or a subject at risk of the occurrence of an autoimmune disease, or a subject suspected of having (or developing), or potentially having (or developing) an autoimmune disease. In some embodiments of methods of screening of the present invention, the subject may have no symptoms of an autoimmune disease. A polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b) in accordance with certain methods of screening of the present invention is as described elsewhere herein in relation to other aspects of the invention. Thus, the description of polypeptides that comprise (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b) elsewhere herein in relation to other aspects of the invention may be applied, mutatis mutandis, to methods of screening of the present invention. In some embodiments (e.g. of methods of screening of the present invention), a lower level in said sample of an antibody that binds to said polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b), in comparison to a control level, is (i) indicative of an autoimmune disease in said subject, (ii) indicative that said subject has an increased likelihood of having an autoimmune disease (e.g. increased likelihood as compared to a control subject or control population), or (iii) indicative that said subject is at risk (e.g. has an increased risk) of developing an autoimmune disease (e.g. has an increased risk as compared to a control subject or control population). In practice, assessment of the disease status of an individual (or subject) is often not limited to simply determining, in a binary fashion, the presence or absence of a disease. It can be advantageous to categorise an individual (or subject) as being of high (or higher) risk or low (or lower) risk of having a condition, i.e. determining the likelihood of the individual (or subject) having the condition. Individuals determined as being high (or having higher or increased) risk may then warrant further assessment (e.g. taking patient history, assessment of clinical symptoms, performance of further tests). The present methods can provide an indication that an individual (subject) has an increased likelihood of having an autoimmune disease. The present methods can also provide an indication that an individual (subject) is at risk of developing an autoimmune disease, which can be advantageous as knowing risk can help guide clinical management (e.g. active monitoring of the individual overtime and / or the performance of further tests). A "lower" (or decreased or reduced) level in comparison to a control level as described herein includes any measurable decrease or reduction of the antibody level when compared with a control level. Preferably, the level is significantly lower (or decreased or reduced) compared to the level found in an appropriate control (e.g. control sample or subject or population). More preferably, the significantly lower (or decreased) levels are statistically significant, preferably with a p-value of <0.05. In some embodiments, a lower (or decreased level) may be a decrease in level of ^2%. 5s 3%, 3s 5%, 3s 10%, 3s 25%, 3s 50%, 3s75%, 3s80%, 3=90%, 3=95% or 3s 99% compared to the level found in an appropriate control sample or subject or population (i.e. when compared to a control level). A “control level” may be the level in a control subject or population (e.g. in a sample(s) that has been obtained from a control subject or population). A “control level” may be a level of an antibody that binds (e.g. specifically binds) to said polypeptide that comprises a bacteriophage polypeptide, fragment or variant where the control level is derived from (or established based on or calculated from) the level in a control subject or population (e.g. in a sample(s) that has been obtained from a control subject or population). Such a population also may be referred to as a reference population. Appropriate control subjects (or populations) or samples would be readily identified by a person skilled in the art (and are discussed elsewhere herein), and preferably are healthy (or normal) subjects (or populations). The control level may correspond to the level of an antibody that binds to said polypeptide comprising a bacteriophage polypeptide, fragment or variant in appropriate control subjects or samples or populations, e.g. may correspond to a cut-off or threshold level or range found in a control or reference population. Control levels may also be referred to as "reference" levels. The control level may be a discrete figure or a range. Although the control level for comparison could be derived by testing an appropriate control subject or set of control subjects (or a control population), the methods of the invention would not necessarily involve carrying out active tests on control subjects as part of the methods of the present invention but would generally involve a comparison with a control level which had been determined previously from control subjects (or a control population) and was known to the person carrying out the methods of the invention. In some embodiments (e.g. of methods of screening of the present invention), the level of said antibody being lower than a control level of an antibody that binds to said polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b), is (i) indicative of an autoimmune disease, (ii) indicative that said subject has an increased likelihood of having an autoimmune disease (e.g. increased likelihood as compared to a control subject or control population), or (iii) indicative that said subject is at risk (e.g. has an increased risk) of developing an autoimmune disease (e.g. has an increased risk as compared to a control subject or control population), wherein said control level has been determined in the same sample type obtained from one or more subjects (e.g. a group or population of subjects) not having an autoimmune disease (e.g. healthy or normal subjects). In some embodiments in which the disease to be screened for is T1D, the level of said antibody being lower than a control level of an antibody that binds to said polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b), is (i) indicative of T1D (ii) indicative that said subject has an increased likelihood of having T1D (e.g. increased likelihood as compared to a control subject or control population), or (iii) indicative that said subject is at risk (e.g. has an increased risk) of developing T1D (e.g. has an increased risk as compared to a control subject or control population), wherein said control level has been determined in the same sample type obtained from one or more subjects (e.g. a group or population of subjects) not having T1D (e.g. healthy or normal subjects). In some embodiments (e.g. of methods of screening of the present invention), the level of said antibody being lower than a control level of an antibody that binds to said polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b), is (i) indicative of an autoimmune disease, (ii) indicative that said subject has an increased likelihood of having an autoimmune disease (e.g. increased likelihood as compared to a control subject or control population), or (iii) indicative that said subject is at risk (e.g. has an increased risk) of developing an autoimmune disease (e.g. has an increased risk as compared to a control subject or control population), wherein said control level is a level that has been determined by determining the level of an antibody that binds to said polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b) in the same sample type obtained from one or more (e.g. a population of) subjects having an autoimmune disease and from one or more subjects (e.g. a population of subjects) not having an autoimmune disease, wherein the control level is a cut-off level that has been derived (or established or determined) to distinguish (or discriminate) between samples from subjects having an autoimmune disease as opposed to samples from subjects not having an autoimmune disease (e.g. healthy or normal subjects). In some embodiments (e.g. of methods of screening of the present invention), the level of said antibody being lower than a control level of an antibody that binds to said polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b), is (i) indicative of an autoimmune disease, (ii) indicative that said subject has an increased likelihood of having an autoimmune disease (e.g. increased likelihood as compared to a control subject or control population), or (iii) indicative that said subject is at risk (e.g. has an increased risk) of developing an autoimmune disease (e.g. has an increased risk as compared to a control subject or control population), wherein said control level is a level that has been determined by determining the level of an antibody that binds to said polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b) in the same sample type obtained from one or more (e.g. a population of) control subjects (e.g. healthy or normal subjects), wherein the control level is a cut-off level that has been derived (or established or determined) to provide (i) an indication of an autoimmune disease, (ii) an indication that a subject has an increased likelihood of having an autoimmune disease or (iii) an indication that a subject is at risk of developing an autoimmune disease when the level of an antibody that binds to said polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b) is lower in comparison thereto. In some embodiments of the invention (e.g. of methods of screening of the present invention), a control level, e.g. cut-off level (or threshold level), can be derived (or determined or established) to provide a level of confidence in (or for) the indication of an autoimmune disease (e.g. T1D), the indication of increased likelihood of having an autoimmune disease, or the indication of risk (e.g. increased risk) of developing an autoimmune disease, for example an (or at least an) 80%, 85%, 90% or 95% level of confidence in (or for) the indication of an autoimmune disease (e.g. T1D) or the indication of increased likelihood of having an autoimmune disease or the indication of the risk of developing an autoimmune disease. Thus, in some embodiments of the invention, a control level, e.g. cut-off level (or threshold level), can be derived (or determined or established) to provide a level of confidence in (or for) the indication of an autoimmune disease (e.g. T1D), in the indication of increased likelihood of having an autoimmune disease, or in the indication of risk (e.g. increased risk) of developing an autoimmune disease when a lower (or decreased) level of an antibody that binds to said polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b) is determined (or observed) in comparison to a control level (e.g. a cut-off or threshold level). For example, a control level, e.g. cut-off level (or threshold level), can be derived (or determined or established) to provide a level of confidence (e.g. an (or at least an) 80%, 85%, 90% or 95% level of confidence) that an indication of an autoimmune disease (e.g. T1D), an indication of increased likelihood of having an autoimmune disease, or an indication of the risk (e.g. increased risk) of developing an autoimmune disease, is accurate (or correct). In some embodiments (e.g. of methods of screening of the present invention), the level of an antibody that binds to said polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b) being a level that has been established as being (or has been determined to be) indicative of the sample being from an autoimmune disease subject as opposed to from a non-autoimmune disease subject (e.g. a healthy subject or a normal subject), is (i) indicative of an autoimmune disease, (ii) indicative that said subject has an increased likelihood of having an autoimmune disease (e.g. increased likelihood as compared to a control subject or control population), or (iii) indicative that said subject is at risk (e.g. has an increased risk) of developing an autoimmune disease (e.g. has an increased risk as compared to a control subject or control population). In another aspect, the present invention provides a method of determining (or assessing) the likelihood of a subject having an autoimmune disease, said method comprising determining the level, in a body fluid sample, of an antibody that binds to a polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b), wherein said sample has been obtained from said subject. Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants, subjects, controls, etc.). For example, in some embodiments of this aspect of the invention, a lower level in said sample of an antibody that binds to said polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b), in comparison to a control level, is indicative that said subject has an increased likelihood of having an autoimmune disease (e.g. increased likelihood as compared to a control subject or control population). In another aspect, the present invention provides a method of determining (or assessing or estimating) the risk of a subject developing an autoimmune disease, said method comprising determining the level, in a body fluid sample, of an antibody that binds to a polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b), wherein said sample has been obtained from said subject. Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants, subjects, controls, etc.). For example, in some embodiments of this aspect of the invention, a lower level in said sample of an antibody that binds to said polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b), in comparison to a control level, is indicative that said subject is at risk (e.g. has an increased risk) of developing an autoimmune disease (e.g. has an increased risk as compared to a control subject or control population). In a further aspect, the present invention provides a method of providing information that is useful in (or for) screening for an autoimmune disease in a subject, said method comprising determining the level, in a body fluid sample, of an antibody that binds to a polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b), wherein said sample has been obtained from said subject. Said information is of course typically the determined (or measured) level of said antibody. Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants, subjects, etc.). As described above, in some aspects and embodiments the present invention provides methods of screening for an autoimmune disease, said methods comprising determining the level, in a body fluid sample, of an antibody. In an alternative aspect, the present invention provides a method of screening for an autoimmune disease in a subject, said method comprising determining the presence and / or level in a body fluid sample, of a bacteriophage polypeptide, or of a polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of a bacteriophage that comprises (or expresses) said bacteriophage polypeptide, wherein said sample has been obtained from said subject. Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophages, bacteriophage polypeptides, subjects, autoimmune diseases, sample types, etc.). Particularly preferred bacteriophage polypeptides are toxins, for example holins. A preferred holin is set forth herein as SEQ ID NO:1. Another preferred bacteriophage polypeptide is set forth herein as SEQ ID NO:2. Preferred bacteriophages include bacteriophage isolates as set out elsewhere herein, or bacteriophages that correspond to such isolates. The presence and / or level of a bacteriophage polypeptide in a body fluid sample may be determined by any suitable means and the skilled person is familiar with suitable means. For example, in some embodiments, an immunoassay (e.g. a fluorescence immunoassay) may be used to determine (or measure or quantify) the presence of and / or the amount of a bacteriophage polypeptide in a body fluid sample. An antibody that is capable of binding (e.g. specifically binding) to a given bacteriophage polypeptide may be used for this purpose. Typically, an antibody capable of binding to a given bacteriophage polypeptide is contacted with a body fluid sample, and the presence and / or amount (or level) of antibody binding (e.g. specific antibody binding) to said bacteriophage polypeptide is determined (or measured or quantified or detected). The presence and / or level, in a body fluid sample, of a polynucleotide (or polynucleotide sequence) that encodes a bacteriophage polypeptide may be determined by any suitable means and the skilled person is familiar with suitable means. For example, in some embodiments, a nucleic acid-based amplification method may be used. In some such embodiments a PCR (polymerase chain reaction) based method may be used. A nucleic acid-based amplification method may be quantitative (e.g. quantitative PCR). The presence and / or level, in a body fluid sample, of a bacteriophage that comprises (or expresses) a bacteriophage polypeptide may be determined by any suitable means. For example, the presence and / or level of said bacteriophage polypeptide in a body fluid sample may be determined, the presence and / or level of said bacteriophage polypeptide being indicative of (or providing a report of) the presence and / or level of the bacteriophage itself. By way of another example, the presence and / or level, in a body fluid sample, of a polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide may be determined, the presence and / or level of said polynucleotide (or polynucleotide sequence) being indicative of (or providing a report of) the presence and / or level of the bacteriophage itself. By way of another example, the presence and / or level, in a body fluid sample, of a bacteriophage that comprises (or expresses) a bacteriophage polypeptide may be determined by determining the presence and / or level (or amount) of a polynucleotide (or polynucleotide sequence) of a bacteriophage genome (or that is part of a bacteriophage genome, or that is expressed or expressible from a bacteriophage genome), wherein the bacteriophage genome encodes (or expresses) said bacteriophage polypeptide. Such polynucleotides (or polynucleotide sequences) of course would not typically be (or correspond to) the full (entire) bacteriophage genome (i.e. not be the polynucleotide sequence of the entire bacteriophage genome), but rather they would typically be a part (or portion) thereof. Said polynucleotide (or polynucleotide sequence) of a bacteriophage genome may, in some embodiments, be a polynucleotide that encodes said bacteriophage polypeptide. In other embodiments, the polynucleotide (or polynucleotide sequence) of a bacteriophage genome (or that is part of a bacteriophage genome, or that is expressed or expressible from a bacteriophage genome) is not a polynucleotide that encodes said bacteriophage polypeptide. The polynucleotide (or polynucleotide sequence) of a bacteriophage genome (or that is part of a bacteriophage genome, or that is expressed or expressible from a bacteriophage genome) may be any polynucleotide (or polynucleotide sequence) of a bacteriophage genome (or that is part of a bacteriophage genome, or that is expressed or expressible from a bacteriophage genome), wherein the bacteriophage genome encodes (or expresses) said bacteriophage polypeptide. The polynucleotide (or polynucleotide sequence) of a bacteriophage genome may be any polynucleotide (or polynucleotide sequence) of a bacteriophage genome (or that is part of a bacteriophage genome, or that is expressed or expressible from a bacteriophage genome), wherein said polynucleotide (or polynucleotide sequence) is characteristic of a genome that encodes said bacteriophage polypeptide. Thus, the polynucleotide (or polynucleotide sequence) may be any bacteriophage genomic sequence (coding or non-coding sequence), or any polynucleotide sequence expressed by (or expressible by) a bacteriophage genome, wherein said polynucleotide (or polynucleotide sequence) is characteristic of (or a marker of) a genome that encodes said bacteriophage polypeptide. Determining the presence and / or level (or amount) of a polynucleotide (or polynucleotide sequence) of a bacteriophage genome (or that is part of a bacteriophage genome, or that is expressed or expressible from a bacteriophage genome) may be done by any suitable means (e.g. a nucleic acid-based amplification method may be used, e.g. as described elsewhere herein). Any type of body fluid sample may be used. In some embodiments of methods of screening of the present invention in which the presence and / or level, in a body fluid sample, of a bacteriophage polypeptide, or of a polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of a bacteriophage that comprises (or expresses) said bacteriophage polypeptide is determined, the body fluid sample may be a faecal sample (or stool sample). Any suitable method for isolating body fluid samples (e.g. faecal samples) may be employed. In some embodiments of methods of screening of the present invention in which the presence and / or level, in a body fluid sample, of a bacteriophage polypeptide, or of a polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of a bacteriophage that comprises (or expresses) said bacteriophage polypeptide is determined, the presence in said sample of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide, or a higher level in said sample of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide in comparison to a control level, is (i) indicative of an autoimmune disease in said subject, (ii) indicative that said subject has an increased likelihood of having an autoimmune disease (e.g. increased likelihood as compared to a control subject or control population), or (iii) indicative that said subject is at risk (e.g. has an increased risk) of developing an autoimmune disease (e.g. has an increased risk as compared to a control subject or control population). In some embodiments of methods of screening of the present invention in which the presence, in a body fluid sample, of a bacteriophage polypeptide, or of a polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of a bacteriophage that comprises (or expresses) said bacteriophage polypeptide is determined, the presence in said sample of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide is (i) indicative of an autoimmune disease in said subject, (ii) indicative that said subject has an increased likelihood of having an autoimmune disease (e.g. increased likelihood as compared to a control subject or control population), or (iii) indicative that said subject is at risk (e.g. has an increased risk) of developing an autoimmune disease (e.g. has an increased risk as compared to a control subject or control population). In some embodiments of methods of screening of the present invention in which the level, in a body fluid sample, of a bacteriophage polypeptide, or of a polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of a bacteriophage that comprises (or expresses) said bacteriophage polypeptide is determined, a higher level in said sample of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide in comparison to a control level, is (i) indicative of an autoimmune disease in said subject, (ii) indicative that said subject has an increased likelihood of having an autoimmune disease (e.g. increased likelihood as compared to a control subject or control population), or (iii) indicative that said subject is at risk (e.g. has an increased risk) of developing an autoimmune disease (e.g. has an increased risk as compared to a control subject or control population). A "higher" (or increased) level in comparison to a control level as described herein includes any measurable increase or elevation of the bacteriophage polypeptide, polynucleotide or bacteriophage when compared with a control level. Preferably, the level is significantly higher (or increased) compared to the level found in an appropriate control (e.g. control sample or subject or population). More preferably, the significantly higher (or increased) levels are statistically significant, preferably with a p-value of <0.05. In some embodiments, a higher (or increased level) may be an increase in level of 2^2%, 2s 3%, 2s 5%, 2s 10%, 2s 25%, 2s 50%, =575%, 2s80%, 2^90%, 2s 95%, 2s100%, 2s2OO%, 2s300%, ^400%, 2s5OO% or =^1000% compared to the level found in an appropriate control sample or subject or population (i.e. when compared to a control level). A “control level” may be the level in a control subject or population (e.g. in a sample(s) that has been obtained from a control subject or population). A “control level” may be a level of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide where the control level is derived from (or established based on or calculated from) the level in a control subject or population (e.g. in a sample(s) that has been obtained from a control subject or population). Such a population also may be referred to as a reference population. Appropriate control subjects (or populations) or samples would be readily identified by a person skilled in the art (and are discussed elsewhere herein), and preferably are healthy (or normal) subjects (or populations). The control level may correspond to the level of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide in appropriate control subjects or samples or populations, e.g. may correspond to a cut-off or threshold level or range found in a control or reference population. Control levels may also be referred to as "reference" levels. The control level may be a discrete figure or a range. Although the control level for comparison could be derived by testing an appropriate control subject or set of control subjects (or a control population), the methods of the invention would not necessarily involve carrying out active tests on control subjects as part of the methods of the present invention but would generally involve a comparison with a control level which had been determined previously from control subjects (ora control population) and was known to the person carrying out the methods of the invention. In some embodiments, the level of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide being higher than a control level of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide, is (i) indicative of an autoimmune disease, (ii) indicative that said subject has an increased likelihood of having an autoimmune disease (e.g. increased likelihood as compared to a control subject or control population), or (iii) indicative that said subject is at risk (e.g. has an increased risk) of developing an autoimmune disease (e.g. has an increased risk as compared to a control subject or control population), wherein said control level has been determined in the same sample type obtained from one or more subjects (e.g. a group or population of subjects) not having an autoimmune disease (e.g. healthy or normal subjects). In some embodiments in which the disease to be screened for is T1D, the level of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide being higher than a control level of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide is (i) indicative of T1D (ii) indicative that said subject has an increased likelihood of having T1D (e.g. increased likelihood as compared to a control subject or control population), or (iii) indicative that said subject is at risk (e.g. has an increased risk) of developing T1D (e.g. has an increased risk as compared to a control subject or control population), wherein said control level has been determined in the same sample type obtained from one or more subjects (e.g. a group or population of subjects) not having T1D (e.g. healthy or normal subjects). In some embodiments, the level of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide being higher than a control level of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide is (i) indicative of an autoimmune disease, (ii) indicative that said subject has an increased likelihood of having an autoimmune disease (e.g. increased likelihood as compared to a control subject or control population), or (iii) indicative that said subject is at risk (e.g. has an increased risk) of developing an autoimmune disease (e.g. has an increased risk as compared to a control subject or control population), wherein said control level is a level that has been determined by determining the level of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide in the same sample type obtained from one or more (e.g. a population of) subjects having an autoimmune disease and from one or more subjects (e.g. a population of subjects) not having an autoimmune disease, wherein the control level is a cut-off level that has been derived (or established or determined) to distinguish (or discriminate) between samples from subjects having an autoimmune disease as opposed to samples from subjects not having an autoimmune disease (e.g. healthy or normal subjects). In some embodiments, the level of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide being higher than a control level of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide is (i) indicative of an autoimmune disease, (ii) indicative that said subject has an increased likelihood of having an autoimmune disease (e.g. increased likelihood as compared to a control subject or control population), or (iii) indicative that said subject is at risk (e.g. has an increased risk) of developing an autoimmune disease (e.g. has an increased risk as compared to a control subject or control population), wherein said control level is a level that has been determined by determining the level of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide in the same sample type obtained from one or more (e.g. a population of) control subjects (e.g. healthy or normal subjects), wherein the control level is a cut-off level that has been derived (or established or determined) to provide (i) an indication of an autoimmune disease, (ii) an indication that a subject has an increased likelihood of having an autoimmune disease or (iii) an indication that a subject is at risk of developing an autoimmune disease when the level of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide is higher in comparison thereto. In some embodiments, a control level, e.g. cut-off level (or threshold level), can be derived (or determined or established) to provide a level of confidence in (or for) the indication of an autoimmune disease (e.g. T1D), the indication of increased likelihood of having an autoimmune disease, or the indication of risk (e.g. increased risk) of developing an autoimmune disease, for example an (or at least an) 80%, 85%, 90% or 95% level of confidence in (or for) the indication of an autoimmune disease (e.g. T1D) or the indication of increased likelihood of having an autoimmune disease or the indication of the risk of developing an autoimmune disease. Thus, in some embodiments of the invention, a control level, e.g. cut-off level (or threshold level), can be derived (or determined or established) to provide a level of confidence in (or for) the indication of an autoimmune disease (e.g. T1D), in the indication of increased likelihood of having an autoimmune disease, or in the indication of risk (e.g. increased risk) of developing an autoimmune disease when a higher (or increased) level of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide is determined (or observed) in comparison to a control level (e.g. a cut-off or threshold level). For example, a control level, e.g. cut-off level (or threshold level), can be derived (or determined or established) to provide a level of confidence (e.g. an (or at least an) 80%, 85%, 90% or 95% level of confidence) that an indication of an autoimmune disease (e.g. T1D), an indication of increased likelihood of having an autoimmune disease, or an indication of the risk (e.g. increased risk) of developing an autoimmune disease, is accurate (or correct). In some embodiments, the level of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide being a level that has been established as being (or has been determined to be) indicative of the sample being from an autoimmune disease subject as opposed to from a non-autoimmune disease subject (e.g. a healthy subject or a normal subject), is (i) indicative of an autoimmune disease, (ii) indicative that said subject has an increased likelihood of having an autoimmune disease (e.g. increased likelihood as compared to a control subject or control population), or (iii) indicative that said subject is at risk (e.g. has an increased risk) of developing an autoimmune disease (e.g. has an increased risk as compared to a control subject or control population). In another aspect, the present invention provides a method of determining (or assessing) the likelihood of a subject having an autoimmune disease, said method comprising determining the level, in a body fluid sample, of a bacteriophage polypeptide, or of a polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of a bacteriophage that comprises (or expresses) said bacteriophage polypeptide, wherein said sample has been obtained from said subject. Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, subjects, controls, etc.). For example, in some embodiments of this aspect of the invention, a higher level in said sample of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide, in comparison to a control level, is indicative that said subject has an increased likelihood of having an autoimmune disease (e.g. increased likelihood as compared to a control subject or control population). In another aspect, the present invention provides a method of determining (or assessing or estimating) the risk of a subject developing an autoimmune disease, said method comprising determining the level, in a body fluid sample, of said bacteriophage polypeptide, or of a polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of a bacteriophage that comprises (or expresses) said bacteriophage polypeptide, wherein said sample has been obtained from said subject. Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, fragments, variants, subjects, controls, etc.). For example, in some embodiments of this aspect of the invention, a higher level in said sample of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide, in comparison to a control level, is indicative that said subject is at risk (e.g. has an increased risk) of developing an autoimmune disease (e.g. has an increased risk as compared to a control subject or control population). In a further aspect, the present invention provides a method of providing information that is useful in (or for) screening for an autoimmune disease in a subject, said method comprising determining the presence and / or level, in a body fluid sample, of a bacteriophage polypeptide, or of a polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of a bacteriophage that comprises (or expresses) said bacteriophage polypeptide, wherein said sample has been obtained from said subject. Said information is of course typically the determined (or measured) level of said bacteriophage polypeptide, or of said polynucleotide (or polynucleotide sequence) that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises (or expresses) said bacteriophage polypeptide. Embodiments of other aspects of the invention described elsewhere herein may be applied, mutatis mutandis, to this aspect of the invention (e.g. preferred bacteriophage polypeptides, subjects, autoimmune diseases, sample types, etc.). As used throughout the entire application, and unless otherwise clear from the context, the terms "a" and "an" are used in the sense that they mean "at least one", "at least a first", "one or more" or "a plurality" of the referenced components or steps, except in instances wherein an upper limit is thereafter specifically stated. Where the terms “comprise”, “comprises”, “comprising”, “has” or “having”, or other equivalent terms are used herein, then in some more specific embodiments these terms include the term “consists of” or “consists essentially of”, or other equivalent terms. LIST OF AMINO ACID (a.a.) SEQUENCES DISCLOSED HEREIN AND THEIR SEQUENCE IDENTIFIERS (SEQ ID NOs) Full-length amino acid sequence of a holin polypeptide encoded by a bacteriophage genome of a bacteriophage of Blautia (SEQ ID NO:1) MIM EQITN YVKPELI WAI ALYFVGM ALKQAQAVKDKYIPLILGGI SI Al CAI YVFATCTCG TGQDIAMAIFTAITQGILIAGLSTYVNQIVKQANKDE Full-length amino acid sequence of a bacteriophage polypeptide encoded by a bacteriophage genome of a bacteriophage of Proteobacter (SEQ ID NO:2) MGPVSTPAVSWVRLLYFLTTLPASFPNILAII Amino acid seguence of a fragment (or portion) of the holin polypeptide of SEQ ID NO:1 (SEQ ID NO:3) IMEQITNYVKPELIWAIAL Amino acid sequence of a fragment (or portion) of the polypeptide of SEQ ID NO:2 (SEQ ID NO:4) RLLYFLTTLPASFPNILAII The invention will be further described with reference to the following nonlimiting Example with reference to the following drawings in which: Figure 1: Box-plot showing that peptide p1_Set38 antibody titres in human serum are significantly higher in healthy controls than in T1D patients. p=0.0006. The figures show data distribution into quartiles. The box represents the interquartile range. “X” shows the mean. On the Y-axis, the values represent Relative Light Units. Figure 2: Box-plot showing that peptide p26_set72 antibody titres in human serum are significantly higher in healthy controls than in T1D patients. p=6x10'8. The figures show data distribution into quartiles. The box represents the interquartile range. “X” shows the mean. On the Y-axis, the values represent Relative Light Units. EXAMPLE Introduction Viruses have been suggested to be connected to T1D (Type 1 Diabetes) etiology. Human viruses have been studied extensively but no specific human virus-related biomarkers have been found. Intestinal bacteria can become infected with bacteriophages, however bacteriophages have not been linked to any disease. In the present study, anti-bacteriophage antibodies as potential biomarkers for T1D have been investigated. Viruses, including bacterial viruses, have many intrinsic adjuvant properties and are recognizable by human immune cell pattern-recognition receptors. The aim of this study was to identify intestinal microbiome-related proteins as possible etiological factors associated with T1D pathogenesis. The present study indicates that bacteriophage polypeptides (e.g. toxins, such as holins) may induce immune dysfunction which leads to autoimmunity. The present study also indicates that relative titres of antibodies (relative titres in T1D subjects as compared to healthy control subjects) to bacteriophage polypeptides may serve as predictive biomarkers. Materials and Methods Patients Serum samples of 40 participants (children and adults) with T1D (i.e. T1D patients) from Tartu University Hospital and 40 controls (healthy children and students, laboratory personnel), matched pairwise for sex and age, all from Estonia , were collected. All T1D patients were on insulin treatment. Sera were collected after written informed consent according to the Declaration of Helsinki. Permission was granted by the Tartu University Ethics committee. Peptides Biotin-conjugated 20-aa peptides (i.e. 20 amino acid long peptides) were synthesized at GenScript (Leiden, the Netherlands). Microarray Antibody titres against the peptides were analyzed at VTT (Espoo, Finland) using an in-house developed high-throughput fluorescent microarray. The array-in-well platform was adjusted to screen the synthetic peptides for their ability to identify disease-related (T1 D-related) antibodies in human sera (by analysing antibody titres in serum samples from T1D patients and from healthy control subjects and assessing whether or not there are different serum antibody titres (or levels) in the two different groups, T1D versus control). The bacteriophage peptides were immobilized on the array surface through biotin-streptavidin interactions, and serum samples were added on top. If a serum sample from an individual contained anti-bacteriophage antibodies that were capable of binding to a peptide under investigation, these antibodies bound to that specific bacteriophage peptide on the array surface and could be detected. The antibacteriophage antibodies in human serum were of course human anti-bacteriophage antibodies. In order to detect and quantify binding of anti-bacteriophage antibodies to immobilized peptides on the array, a fluorescently labelled anti-human secondary antibody was used. Results Candidate peptide design was based on metagenome sequencing data of the EU DIABIMMUNE study (project no. 202063) cohort and was comprised of faecal microbiome samples collected from Tartu, Estonia, Petrozavodsk, Russia and Espoo, Finland. The analysis of the metagenome sequencing data (PRJNA497734) was published in 2015 (Kostic et al. 2015), (Vatanen et al. 2019), however, no disease-associated proteins were proposed. However, despite the fact that no disease-associated proteins were proposed , we have found that when peptides derived from certain bacteriophage proteins were analysed for binding to antibodies in serum samples obtained from T1D subjects and healthy controls, different antibody levels (titres) were observed between the two groups. Two peptides displayed significantly different antibody titres between diabetic and control group. Remarkably, the titres are significantly higher in the control group as compared to the T1D group. One of the peptides (p1_Set38) belongs to a known toxin family (the holin family). All sera tested positive for antibodies that bind to this peptide, with the median in the control group being 3 times higher than in the T1D group (Figure 1). This peptide (p1_Set38) represents a fragment (or a portion) of a previously unknown holin family member that appears to be a local variant belonging to two bacteriophages. The amino acid sequence of the p1_Set38 peptide is set out elsewhere herein as SEQ ID NO:3. This peptide represents a fragment of a holin protein, said holin protein having the amino acid sequence set out elsewhere herein as SEQ ID NO:1. This holin protein (SEQ ID NO:1) is encoded by a bacteriophage genome of a bacteriophage of the bacterial genus Blautia. The other peptide is p26_set72. The amino acid sequence of the p26_set72 peptide is set out elsewhere herein as SEQ ID NO:4. This peptide represents a fragment of a bacteriophage protein, said bacteriophage protein having the amino acid sequence set out elsewhere herein as SEQ ID NO:2. p26_set72 represents a fragment (or a portion) of a protein found in a bacteriophage genome of a Proteobacter bacteriophage. Signals in the control group were also higher than in the T1D group with the p26_set72 peptide (Figure 2). Discussion The results indicate that certain bacteriophage antigens (polypeptides) are associated with T1D, since the results herein show highly significant differences in antibody levels (or titres) between T1D and controls. Surprisingly, the antibody titres are significantly higher in healthy controls. This indicates that the antibodies are protective. In this regard, and without wishing to be bound by theory, we believe that autoimmunity is triggered by bacteriophage proteins (e.g. bacteriophage proteins from which the peptides described above are derived, such as holin proteins) if antibody production against these bacteriophage proteins is inefficient. Human proteins Bax and Bak, which are involved in programmed cell death, are considered holin homologues and may have evolved from bacterial holins. Bax / Bak genes can functionally replace holin gene in lambda phage. Holins insert into eukaryotic cell membranes. In human cells, lambda phage holin has been shown to localize to the endoplasmic reticulum and mitochondria by subcellular fractionation and organelle-specific fluorescence. In light of the finding in the present study that there are higher titres (levels) of anti-bacteriophage antibodies that bind to certain bacteriophage polypeptides in the serum of control subjects as compared to in T1D subjects, it is believed that bacteriophage polypeptides (or fragments or variants thereof) would be useful as vaccines to prevent (or treat) autoimmune diseases (e.g. T1D). Without wishing to be bound by theory, such vaccines would provide a protective immune response in the subject to which the vaccine has been administered, enabling the subject to produce antibodies that bind to the bacteriophage protein in question and protect against the induction of autoimmunity by said bacteriophage protein (e.g. a bacteriophage toxin such as a holin). Without wishing to be bound by theory, it is believed that bacteriophage proteins such as toxins (e.g. holins), or fragments or variants thereof, would elicit an immune response when administered to a subject and provide immune protection (vaccination) against a bacteriophage polypeptide (such as a toxin, e.g. a holin) that may otherwise cause necrosis and subsequent autoimmunity triggered by necrosis. Of particular note, we have identified a bacterial toxin (a holin) as a target for protective antibodies, said toxin (or fragments or variants thereof) representing a potential vaccine candidate. Also, based on the findings of the present study, bacteriophage polypeptides (or fragments or variants thereof) may be used as tools for screening (e.g. risk estimation) as they enable the detection of certain anti-bacteriophage protein antibodies in samples from subjects, and it has been demonstrated that such antibodies are present at different levels in samples from T1D subjects as compared to healthy subjects. Such bacteriophage polypeptides (or fragments or variants thereof) could be included in screening kits (e.g. for risk estimation of T1D). References Kostic, A.D. etal., 2015. The dynamics of the human infant gut microbiome in development and in progression toward type 1 diabetes. Cell Host and Microbe, 17 (2), 260-273. doi:10.1016 / j.chom.2015.01.001. Vatanen, T. et al., 2019. Genomic variation and strain-specific functional adaptation in the human gut microbiome during early life. Nature Microbiology, 4 (3), 470-479. doi:10.1038 / s41564-018-0321-5.

Claims

1. A polypeptide for use in preventing or treating an autoimmune disease in a subject, wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b).

2. The polypeptide for use of claim 1, wherein said autoimmune disease is type 1 diabetes.

3. The polypeptide for use of claim 1 or claim 2, wherein said bacteriophage is a bacteriophage of the gut microbiota.

4. The polypeptide for use of any one of claims 1 to 3, wherein said bacteriophage polypeptide is, or corresponds to, a toxin.

5. The polypeptide for use of any one of claims 1 to 4, wherein said bacteriophage polypeptide is, or corresponds to, a holin.

6. The polypeptide for use of any one of claims 1 to 5, wherein said bacteriophage is a bacteriophage of Clostridia.

7. The polypeptide for use of any one of claims 1 to 6, wherein saidbacteriophage polypeptide has the amino acid sequence of: MIMEQITNYVKPELIWAIALYFVGMALKQAQAVKDKYIPLILGGISIAICAIYVFA TCTCGTGQDIAMAIFTAITQGILIAGLSTYVNQIVKQANKDE (SEQ ID NO:1).

8. The polypeptide for use of any one of claims 1 to 5, wherein said bacteriophage is a bacteriophage of Proteobacter.

9. The polypeptide for use of any one of claims 1 to 5 or 8, wherein said bacteriophage polypeptide has the amino acid sequence of: MGPVSTPAVSWVRLLYFLTTLPASFPNILAII (SEQ ID NO:2).

10. The polypeptide for use of any one of claims 1 to 7, wherein said polypeptide comprises a fragment of a bacteriophage polypeptide or a variant thereof.

11. The polypeptide for use of any one of claims 1 to 10, wherein said fragment is 10 to 30, preferably 15 to 25 amino acids in length.

12. The polypeptide for use of any one of claims 1 to 7, 10 or 11, wherein said fragment has the amino acid sequence of IMEQITNYVKPELIVVAIAL (SEQ ID NO:3) or a variant thereof.

13. The polypeptide for use of any one of claims 1 to 5 or 8 to 11, wherein said fragment has the amino acid sequence of RLLYFLTTLPASFPNILAII (SEQ ID NO:4) or a variant thereof.

14. A nucleic acid molecule encoding a polypeptide as defined in any preceding claim for use in preventing or treating an autoimmune disease in a subject.

15. The nucleic acid molecule for use of claim 14, wherein said autoimmune disease is Type 1 diabetes.

16. A method of preventing or treating an autoimmune disease, said method comprising administering to a subject in need thereof a therapeutically effective amount of a polypeptide or a nucleic acid molecule encoding said polypeptide, wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b).

17. Use of a polypeptide, or a nucleic acid molecule encoding said polypeptide, in the manufacture of a medicament for preventing or treating an autoimmune disease, wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b).

18. A vaccine composition comprising a polypeptide or a nucleic acid molecule encoding said polypeptide, wherein said polypeptide comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b), and a diluent, excipient or carrier, preferably wherein said polypeptide is as defined in any one of claims 3 to 13.

19. The vaccine composition of claim 18, wherein said composition further comprises an adjuvant.

20. An isolated polypeptide comprising a fragment of the amino acid sequence of SEQ ID NO:1 or a variant thereof, or comprising a fragment of the amino acid sequence of SEQ ID NO:2 or a variant thereof, wherein said isolated polypeptide does not comprise SEQ ID NO:1 or SEQ ID NO:2.

21. The isolated polypeptide of claim 20, wherein said isolated polypeptide comprises the amino acid sequence of SEQ ID NO:3 or a variant thereof or comprises the amino acid sequence of SEQ ID NO:4 or a variant thereof.

22. An isolated nucleic acid molecule that encodes the polypeptide of claim 20 or claim 21.

23. A method of screening for an autoimmune disease in a subject, said method comprising determining the level, in a body fluid sample, of an antibody that binds to a polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b), wherein said sample has been obtained from said subject.

24. The method of claim 23, wherein a lower level in said sample of an antibody that binds to said polypeptide that comprises (a) a bacteriophage polypeptide, (b) a fragment of a bacteriophage polypeptide, or (c) a variant of (a) or (b), in comparison to a control level, is (i) indicative of an autoimmune disease in said subject, (ii) indicative that said subject has an increased likelihood of having an autoimmune disease, or (iii) indicative that said subject is at risk of developing an autoimmune disease.

25. The method of any one of claims 16, 23 or 24, or the use of claim 17, wherein said autoimmune disease or said polypeptide is as defined in any preceding claim.

26. A method of screening for an autoimmune disease in a subject, said method comprising determining the presence and / or level, in a body fluid sample, of a bacteriophage polypeptide, or of a polynucleotide that encodes said bacteriophage polypeptide, or of a bacteriophage that comprises said bacteriophage polypeptide, wherein said sample has been obtained from said subject.

27. The method of claim 26, wherein the presence in said sample of said bacteriophage polypeptide, or of said polynucleotide that encodes said bacteriophage polypeptide, or of said bacteriophage that comprises said bacteriophage polypeptide, or a higher level in said sample of said5 bacteriophage polypeptide, or of said polynucleotide that encodes saidbacteriophage polypeptide, or of said bacteriophage that comprises said bacteriophage polypeptide in comparison to a control level is (i) indicative of an autoimmune disease in said subject, (ii) indicative that said subject has an increased likelihood of having an autoimmune disease, or (iii) indicative that10 said subject is at risk of developing an autoimmune disease.

28. The method of claim 26 or claim 27, wherein said autoimmune disease is as defined in claim 2 and / or said bacteriophage or bacteriophage polypeptide is as defined in any one of claims 3 to 9.

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