Toxin-related antibodies with antimicrobial and antiviral activity

Anti-idiotypic antibodies which recognise the idiotope of an antibody specific for a yeast killer toxin possess microbicidal activity. Fragments (e.g. decapeptides) of these anti-idiotypic antibodies, particularly those comprising CDR residues, also show microbicidal activity, as do peptides having the same sequence but composed of D-amino acids, or including amino acid substitutions. Peptidomimetics of these microbicidal polypeptides are also provided. Antiviral activity is also seen.