title: An altered camelid-like single domain anti-idiotypic antibody fragment of HM-1 killer toxin: acts as an effective antifungal agent.
abstract: Phage-display and competitive panning elution leads to the identification of minimum-sized antigen binders together with conventional antibodies from a mouse cDNA library constructed from HM-1 killer toxin neutralizing monoclonal antibody (nmAb-KT). Antigen-specific altered camelid-like single-domain heavy chain antibody (scFv K2) and a conventional antibody (scFv K1) have been isolated against the idiotypic antigen nmAb-KT. The objectives of the study were to examine (1) their properties as compared to conventional antibodies and also (2) their antifungal activity against different pathogenic and non-pathogenic fungal species. The alternative small antigen-binder, i.e., the single-domain heavy chain antibody, was originated from a conventional mouse scFv phage library through somatic hyper-mutation while selection against antigen. This single-domain antibody fragment was well expressed in bacteria and specifically bound with the idiotypic antigen nmAb-KT and had a high stability and solubility. Experimental data showed that the binding affinity for this single-domain antibody was 272-fold higher (K(d)=1.07×10(-10) M) and antifungal activity was three- to fivefold more efficient (IC(50)=0.46×10(-6) to 1.17×10(-6) M) than that for the conventional antibody (K(d)=2.91×10(-8) M and IC(50)=2.14×10(-6) to 3.78×10(-6) M). The derived single-domain antibody might be an ideal scaffold for anti-idiotypic antibody therapy and the development of smaller peptides or peptide mimetic drugs due to their less complex antigen-binding site. We expect that such single-domain synthetic antibodies will find their way into a number of biotechnological or medical applications.
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: M Enamul
authors.initials: ME
authors.lastname: Kabir
authors.forename: Senthilkumar
authors.initials: S
authors.lastname: Krishnaswamy
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: D000595:Amino Acid Sequence; D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology*; D000908:Antibodies, Fungal / Q000737:chemistry* / Q000302:isolation & purification; D000911:Antibodies, Monoclonal / Q000378:metabolism; D000935:Antifungal Agents / Q000737:chemistry / Q000276:immunology / Q000494:pharmacology*; D015153:Blotting, Western; D002176:Candida albicans / Q000187:drug effects; D003455:Cryptococcus neoformans / Q000187:drug effects; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D007128:Immunoglobulin Fragments / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D020128:Inhibitory Concentration 50; D055646:Killer Factors, Yeast / Q000276:immunology*; D051379:Mice; D008969:Molecular Sequence Data; D019151:Peptide Library; D012441:Saccharomyces cerevisiae / Q000187:drug effects; D057127:Single-Chain Antibodies / Q000737:chemistry / Q000378:metabolism
chemical_list: D000888:Antibodies, Anti-Idiotypic; D000908:Antibodies, Fungal; D000911:Antibodies, Monoclonal; D000935:Antifungal Agents; D007128:Immunoglobulin Fragments; D055646:Killer Factors, Yeast; D019151:Peptide Library; D057127:Single-Chain Antibodies