Yeast killer toxin-like antibodies in experimental and clinical candidasis

Abstract

This chapter focuses on studies that used the yeast killer phenomenon and yeast killer toxin (YKT) to develop potentially candidacidal yeast killer toxins-like antibodies. The activity of killer toxins against many opportunistic yeasts prompted some of researchers to evaluate the potential therapeutic effect of a YKT secreted from Pichia anomala on experimental Pytiriasis versicolor-like lesions and otitis externa in experimental animal models. It was supposed that antibodies, or their engineered derivatives, interacting with the physiological target of YKT, such as the cell wall receptors of sensitive microorganisms, may present minor or no side effects. Following this line of research, strong evidence was obtained as to the induction of YKT-like antibodies by appropriate idiotypic vaccination. Theoretically, the interaction between the functional epitope of P. anomala YKT and the specific cell wall receptor (KTR) on Candida albicans cells may be imagined to be potentially reproduced by the steric complementarity between the idiotype of a YKT neutralizing monoclonal antibody and at least one of its anti-Id antibodies, according to the idiotypic network theory. To test this hypothesis, a murine mAb (mAb KT4; IgGl) was selected among those produced against a YKT secreted by a P. anomala strain (KT25F) (ATCC 96603) and characterized by a wide spectrum of antimicrobial activity.