Therapeutic activity of an engineered synthetic killer antiidiotypic antibody fragment against experimental mucosal and systemic candidiasis.
Peptides derived from the sequence of a single-chain, recombinant, antiidiotypic antibody (IdAb; KT-scFv) acting as a functional internal image of a microbicidal, wide-spectrum yeast killer toxin (KT) were synthesized and studied for their antimicrobial activity by using the KT-susceptible Candida albicans as model organism. A decapeptide containing the first three amino acids (SAS) of the light chain CDR1 was selected and optimized by alanine replacement of a single residue. This peptide exerted a strong candidacidal activity in vitro, with a 50% inhibitory concentration of 0.056 microM, and was therefore designated killer peptide (KP). Its activity was neutralized by laminarin, a beta1-3 glucan molecule, but not by pustulan, a beta1-6 glucan molecule. KP also competed with the binding of a KT-like monoclonal IdAb to germinating cells of the fungus. In a rat model of vaginal candidiasis, local, postchallenge administration of KP was efficacious in rapidly abating infections caused by fluconazole-susceptible or -resistant C. albicans strains. In systemic infection of BALB/c or SCID mice preinfected intravenously with a lethal fungal load, KP caused a highly significant prolongation of the median survival time, with >80% of the animals still surviving after >60 days, whereas >90% of control mice died within 3 to 5 days. KP is therefore the first engineered peptide derived from a recombinant IdAb retaining KT microbicidal activity, probably through the interaction with the beta-glucan KT receptor on target microbial cells.
Sezione di Microbiologia, Dipartimento di Patologia e Medicina di Laboratorio, Università degli Studi di Parma, Parma, Italy.
Luciano
L
Polonelli
Walter
W
Magliani
Stefania
S
Conti
Luisa
L
Bracci
Luisa
L
Lozzi
Paolo
P
Neri
Daniela
D
Adriani
Flavia
F
De Bernardis
Antonio
A
Cassone
D000595:Amino Acid Sequence; D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000627:therapeutic use*; D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D001483:Base Sequence; D002177:Candidiasis / Q000628:therapy*; D002181:Candidiasis, Vulvovaginal / Q000628:therapy*; D005260:Female; D005936:Glucans; D007128:Immunoglobulin Fragments / Q000627:therapeutic use*; D055646:Killer Factors, Yeast; D051379:Mice; D008807:Mice, Inbred BALB C; D016513:Mice, SCID; D008969:Molecular Sequence Data; D009183:Mycotoxins / Q000276:immunology*; D009842:Oligopeptides / Q000627:therapeutic use*; D010455:Peptides / Q000627:therapeutic use*; D011134:Polysaccharides / Q000494:pharmacology; D015202:Protein Engineering; D051381:Rats; D011994:Recombinant Proteins / Q000627:therapeutic use
D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D005936:Glucans; D007128:Immunoglobulin Fragments; C524619:KP killer peptide; D055646:Killer Factors, Yeast; D009183:Mycotoxins; D009842:Oligopeptides; D010455:Peptides; D011134:Polysaccharides; D011994:Recombinant Proteins; C055966:immunoglobulin Fv; C087906:killer toxin, Pichia; C008247:laminaran