In vitro activity of a monoclonal killer anti-idiotypic antibody and a synthetic killer peptide against oral isolates of Candida spp. differently susceptible to conventional antifungals

Background/aims: A monoclonal killer anti-idiotypic antibody (mAbK10) and a synthetic killer peptide, acting as internal images of a microbicidal, wide-spectrum yeast killer toxin (KT) have been recently shown to express candidacidal in vitro and an in vivo therapeutic activity against experimental mucosal and systemic candidosis models caused by a reference strain of Candida albicans (10S). Material and methods: The in vitro candidacidal activity of mAbK10 and synthetic killer peptide was compared using a colony forming unit assay against a large number of isolates of different Candida spp., obtained from oral saliva of adult diabetic (type 1 and 2) and nondiabetic subjects from Parma (Italy) and London (UK). Results: Both the KT-mimics exerted a strong dose-dependent candidacidal activity, probably mediated by the interaction with β-glucan KT receptors on target yeast cells, against all the tested strains, regardless of their species and pattern of resistance to conventional antifungal agents. Conclusions: These observations open new perspectives in the design and production of candidacidal compounds whose mechanism reflects that exerted in nature by killer yeasts.