Production of colicin V in vitro and in vivo and observations on its effects in experimental animals

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Abstract
In recent years, a possible relationship between pathogenicity and colicinogeny in some Escherichia coli strains responsible for gastrointestinal infection and bacteremia in man and animals was inferred. Enterotoxigen-negative, colicin V-producing E. coli strains were used to elaborate a simple in vitro method for producing greater yields of colicin V free of bacterial cells and large, non-dialyzable molecules; to detect the presence of the bacteriocin in peritoneal fluids of moribund mice injected i.p. 18 h previously with colicin V-producing strains (in these mice, Col V+ exconjugants survived and multiplied more extensively than the Col V- recipient strains from which they were derived); and to observe an increased vascular permeability and inflammatory response in rabbits and guinea pigs when a culture supernatant demonstrating colicin activity was injected intradermally. The vascular response obtained after the injection of a colicin V-containing dialysate alone or that of a trypsinized colicin-containing supernatant was always smaller than when the colicin V-active supernatant was injected. An enterotoxin-free dialysate containing colicin V also markedly increased the mild inflammatory reaction that occurred in rabbit and guinea pig skin when purified endotoxin was injected s.c. in microgram doses. Colicin V may act as a virulence factor in some E. coli strains.