Bacterial vaginosis diagnostic

A composition comprising:

• (a) an antibody specific for the de-sialylated form of the peptide comprising SEQ ID NO:
• 11, 12, 13, 14, 15, or 16, preferably specific for an epitope that is present in the peptide motif Cyc-DAla-Ser[Gal]-DAla-Arg and that is absent or cryptic in the corresponding sialylated peptide motif Cyc-DAla-Ser[Gal-Sial]-DAla-Arg;
• or
• (b) an antibody having a heavy chain with 3 CDRs and a light chain with 3 CDRs, wherein the heavy chain CDR1 has SEQ ID NO:1;
• the heavy chain CDR2 has SEQ ID NO:2;
• the heavy chain CDR3 has SEQ ID NO:3;
• the light chain CDR1 has SEQ ID NO:
• 4;
• the light chain CDR2 has SEQ ID NO:
• 5;
• and the light chain CDR3 has SEQ ID NO:
• 6, preferably wherein the heavy chain has SEQ ID NO:
• 7 and/or the light chain has SEQ ID NO:
• 8;
• or
• (c) an indicator molecule suitable for use in detecting the presence in a test sample of cleavage activity of a sialidase enzyme, the indicator molecule comprising a capture site and a peptide comprising:
• (i) Cyc-DAla-Ser[Gal-Sial]-DAla-Arg-PEG-Biotin;
• (ii) Biotin-PEG-Asp-Glu-DSer-Nva-Cyc-DAla-Ser[Gal-Sial]-DAla-Arg-Phe-DSer-Val;
• (iii) Biotin-PEG-Asp-Arg-DAla-BIP-Ser-Pro-Ser[Gal-Sial]-DAla-DAsp-Ser;
• (iv) Biotin-PEG-Asp-Ser-Ser(PO3)-DAla-Ile-Orn-Ser[Gal-Sial]-DAla-Nle-Glu;
• (v) Biotin-PEG-Asp-DAla-Arg-Nva-DSer-βAla-DAla-Nle-Ser[Gal-Sial]-BIP-Orn-DAla-Glu-Ser;
• or
• (vi) Biotin-PEG-Asp-Thr-DAla-Nle-Glu-DAla-Arg-βAla-Cyc-Orn-DSer-Pro-Ser[Gal-Sial]-βAla-Nva-DSer-Glu-Thr-Cha-DSer-Val;
• or
• (d) an indicator molecule suitable for use in detecting the presence in a test sample of cleavage activity of a sialidase enzyme, the indicator molecule comprising a capture site and a peptide comprising:
• X1-X2-X3[Gal-Sial]-X4-X5
• wherein:
• Sial is a sialyl group;
• X3 is an amino acid comprising a glycosyl acceptor group and is selected from Ser, Thr, Tyr, Hyl, Hyp, Asn, Arg or phosphoserine (SEP), preferably wherein X3 is Ser;
• and
• X1, X2, X4 and X5 are independently selected from any amino acid provided that at least one, preferably at least 2 or 3, of X1, X2, X4 and X5 is a D-amino acid and/or a non-standard amino acid or a non-natural amino acid;
• or
• (e) a peptide comprising SEQ ID NO:
• 11, 12, 13, 14, 15 or 16.

A method for detecting the presence or absence in a test sample of cleavage activity of a sialidase enzyme, the method comprising:

• (i) bringing an indicator molecule into contact with the test sample, wherein the indicator molecule comprises
• (a) a peptide comprising the following sequence:
• (SEQ ID NO:
• 17)
• X1-X2-X3[Gal-Sial]-X4-X5
• wherein:
• Sial is a sialyl group;
• X3 is an amino acid comprising a glycosyl acceptor group and is selected from Ser, Thr, Tyr, Hyl, Hyp, Asn, Arg or phosphoserine (SEP), preferably wherein X3 is Ser;
• and
• X1, X2, X4 and X5 are independently selected from any amino acid provided that at least one, preferably at least two or three, of X1, X2, X4 and X5 is a D-amino acid and/or a non-standard amino acid or a non-natural amino acid;
• and
• b) a capture site which remains intact following cleavage of the sialyl group from the indicator molecule by a sialidase enzyme present in the test sample;
• (ii) adding to the test sample binding molecules capable of binding to the de-sialylated derivative of the indicator molecule, wherein the binding molecules are incapable of binding to the indicator molecule unless and until cleavage of the sialyl group from the indicator molecule by sialidase enzyme present in the sample has occurred;
• (iii) capturing the de-sialylated derivative of the indicator molecule at a capture zone through binding of capture molecules in the capture zone to the capture site, said capture molecules being able to bind to the capture site irrespective of whether or not the indicator molecule has been cleaved;
• and
• (iv) detecting cleavage of the sialyl group from the indicator molecule by determining binding of the binding molecules to the de-sialylated derivative of the indicator molecule captured in the capture zone.