Recombinant single-chain anti-idiotypic antibody: an effective fungal beta-1,3-glucan synthase inhibitor.

Recombinant single-chain fragment variable anti-idiotypic antibodies were produced to represent the internal image of HM-1 killer toxin and were used as novel and effective antifungal agents to inhibit in vitro beta-1,3-glucan synthase and cell growth. The mechanism of cytocidal activity of anti-idiotypic antibodies was investigated and was compared with the actions of aculeacin A and papulacandin B, the most common antibiotics acting as beta-1,3-glucan synthase inhibitors. The degree of inhibition of beta-1,3-glucan synthase by both antibodies and antibiotics were examined for yeasts Saccharomyces cerevisiae A451, Cryptococcus albidus NBRC 0612 and Candida albicans IFM 40215. Although the mechanism of actions of the anti-idiotypic antibodies and antibiotics seems identical, the IC(50) values for the various yeasts used in this study confirmed that anti-idiotypic antibodies could be used as more effective fungal beta-1,3-glucan synthase inhibitors than those of antibiotics.