title: Inhibition of fungal beta-1,3-glucan synthase and cell growth by HM-1 killer toxin single-chain anti-idiotypic antibodies.
abstract: Single-chain variable-fragment (scFv) anti-idiotypic antibodies of an HM-1 killer toxin (HM-1) from the yeast Williopsis saturnus var. mrakii IFO 0895 have been produced by recombinant DNA technology from the splenic lymphocytes of mice immunized by idiotypic vaccination with a neutralizing monoclonal antibody (nMAb-KT). The fungicidal activity of scFv anti-idiotypic antibodies against the isolates of four Candida species was assessed by MIC analysis. scFv antibodies were fungicidal at concentrations of 1.56 to 12.5 microg/ml in vitro against four Candida species. The scFv antibodies exerted a strong candidacidal activity in vitro, with 50% inhibitory concentration (IC(50)) values ranging from 7.3 x 10(-8) to 16.0 x 10(-8) M, and were neutralized by adsorption with nMAb-KT. Furthermore, all scFv antibodies effectively inhibited fungal beta-1,3-glucan synthase activity in vitro, with IC(50) values ranging from 2.0 x 10(-8) to 22.7 x 10(-8) M, values which almost coincide with the values that are inhibitory to the growth of fungal cells. Binding assays showed that the scFv antibodies specifically bind to nMAb-KT, and this binding pattern was confirmed by surface plasmon resonance analysis. The binding ability was further demonstrated by the competition observed between scFv antibodies and HM-1 to bind nMAb-KT. To the best of our knowledge, this is the first study to show that an antifungal anti-idiotypic antibody, in the form of recombinant scFv, potentially inhibits beta-1,3-glucan synthase activity.
authors.affiliation: Department of Biochemistry, Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, 265-1 Higashijima, Niigata 956-8603, Japan.
authors.forename: Dakshnamurthy
authors.initials: D
authors.lastname: Selvakumar
authors.forename: Masahiko
authors.initials: M
authors.lastname: Miyamoto
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Furuichi
authors.forename: Tadazumi
authors.initials: T
authors.lastname: Komiyama
mesh_terms: D000888:Antibodies, Anti-Idiotypic / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology*; D000935:Antifungal Agents / Q000737:chemistry / Q000276:immunology / Q000494:pharmacology*; D001667:Binding, Competitive; D002175:Candida / Q000187:drug effects / Q000201:enzymology / Q000302:isolation & purification; D005964:Glucosyltransferases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D007128:Immunoglobulin Fragments / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D055646:Killer Factors, Yeast; D007700:Kinetics; D008826:Microbial Sensitivity Tests; D008858:Microscopy, Phase-Contrast / Q000379:methods; D009183:Mycotoxins / Q000276:immunology* / Q000378:metabolism; D019151:Peptide Library; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology
chemical_list: D000888:Antibodies, Anti-Idiotypic; D000935:Antifungal Agents; D007128:Immunoglobulin Fragments; D055646:Killer Factors, Yeast; D009183:Mycotoxins; D019151:Peptide Library; D005964:Glucosyltransferases; C020570:1,3-beta-glucan synthase