title: HlyA knock out yields a safer Escherichia coli A0 34/86 variant with unaffected colonization capacity in piglets.
abstract: Escherichia coli A0 34/86 (O83:K24:H31) has been successfully used for prophylactic and therapeutic intestinal colonization of premature and newborn infants, with the aim of preventing nosocomial infections. Although E. coli A0 34/86 was described as a nonpathogenic commensal, partial sequencing revealed that its genome harbours gene clusters highly homologous to virulence determinants of different types of E. coli, including closely linked genes of the alpha-haemolysin operon (hlyCABD) and for the cytotoxic necrotizing factor (cnf1). A haemolysin-deficient mutant (Delta hlyA) of E. coli A0 34/86 was generated and its colonization capacity was determined. The results show that a single dose of the A0 34/86 wild-type or Delta hlyA strains resulted in efficient intestinal colonization of newborn conventional piglets, and that this was still considerable after several weeks. No difference was observed between the wild-type and the mutant strains, showing that haemolysin expression does not contribute to intestinal colonization capacity of E. coli A0 34/86. Safety experiments revealed that survival of colostrum-deprived gnotobiotic newborn piglets was substantially higher upon colonization by the nonhaemolytic strain than following inoculation by its wild-type ancestor. We suggest that the E. coli A0 34/86 Delta hlyA mutant may represent a safer prophylactic and/or immunomodulatory tool with unaffected colonization capacity.
authors.affiliation: Laboratory of Molecular Biology of Bacterial Pathogens, Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
authors.forename: Valeria
authors.initials: V
authors.lastname: Sheshko
authors.forename: Jana
authors.initials: J
authors.lastname: Hejnova
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Rehakova
authors.forename: Jiri
authors.initials: J
authors.lastname: Sinkora
authors.forename: Martin
authors.initials: M
authors.lastname: Faldyna
authors.forename: Pavel
authors.initials: P
authors.lastname: Alexa
authors.forename: Jurgen
authors.initials: J
authors.lastname: Felsberg
authors.forename: Radomira
authors.initials: R
authors.lastname: Nemcova
authors.forename: Alojz
authors.initials: A
authors.lastname: Bomba
authors.forename: Peter
authors.initials: P
authors.lastname: Sebo
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000235:genetics; D002874:Chromosome Mapping / Q000379:methods; D004926:Escherichia coli / Q000235:genetics* / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000382:microbiology / Q000517:prevention & control / Q000662:veterinary*; D029968:Escherichia coli Proteins / Q000235:genetics; D017353:Gene Deletion; D008040:Genetic Linkage; D006460:Hemolysin Proteins / Q000235:genetics; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology*; D013556:Swine, Miniature
chemical_list: D001427:Bacterial Toxins; D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C036507:Hlya protein, E coli; C060296:cytotoxic necrotizing factor type 1