HlyA knock out yields a safer Escherichia coli A0 34/86 variant with unaffected colonization capacity in piglets

• Published in: FEMS immunology and medical microbiology 2006-11, Vol.48 (2), p.257-266
• Main Authors: Sheshko, Valeria, Hejnova, Jana, Rehakova, Zuzana, Sinkora, Jiri, Faldyna, Martin, Alexa, Pavel, Felsberg, Jurgen, Nemcova, Radomira, Bomba, Alojz, Sebo, Peter
• Format: Article
• Language: English
• Subjects: Animals; Bacteria; Bacterial Toxins - genetics; Bacteriology; Biological and medical sciences; Chromosome Mapping - methods; Colonization; Colostrum; Cytotoxic necrotizing factor 1; Cytotoxicity; Deficient mutant; E coli; Escherichia coli; Escherichia coli - genetics; Escherichia coli - pathogenicity; Escherichia coli Infections - microbiology; Escherichia coli Infections - prevention & control; Escherichia coli Infections - veterinary; Escherichia coli Proteins - genetics; Fundamental and applied biological sciences. Psychology; Gene clusters; Gene Deletion; Gene sequencing; Genetic Linkage; Genomes; germ‐free piglets; Gnotobiotic; haemolysin; Hemolysin Proteins - genetics; Homology; Immunomodulation; Infants; Inoculation; Intestine; Microbiology; Miscellaneous; Nosocomial infection; safety; Swine; Swine Diseases - microbiology; Swine, Miniature; Virulence
• ISSN: 0928-8244; 1574-695X; 2049-632X
• DOI: 10.1111/j.1574-695X.2006.00140.x

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 α-haemolysin operon (hlyCABD) and for the cytotoxic necrotizing factor (cnf1). A haemolysin-deficient mutant (ΔhlyA) 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 ΔhlyA 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 ΔhlyA mutant may represent a safer prophylactic and/or immunomodulatory tool with unaffected colonization capacity.