engleski

Distinctive patterns of attaching-effacing activity and diarrhea production of porcine F4ac^+ enterotoxigenic Escherichia coli (ETEC) and non-ETEC strains

The objectives of this work were to verify whether F4ac^+ ETEC strain M1823 (LT^+STb^+) and F4ac^+ (1466 and 2407) or F4ac^- (1467) non-ETEC (LT^- STb^-) strains would induce diarrheal disease in weaned pigs, and to examine whether adherence/lesion patterns were or were not related to the fimbrial and/or enterotoxin antigens. Five 4-week-old pigs were intragastrically inoculated with either 10^10 CFU of ETEC or non-ETEC strains in 60 ml of TSB (principals) or with TSB only (controls). Three of 5 M1823-infected pigs, and 2/5 or 1/5 of 1466- or 2407-infected pigs, respectively, developed diarrhea 6 days after the inoculation. The pigs infected with strain M1823 gained a smaller percentage of initial weight (2.8%) than control pigs (26.3%) or those inoculated with strain 2407 (32.1%). The number of E. coli in the jejunum of pigs infected with strain M1823 was significantly higher (P < 0.05) than that in the pigs inoculated with F4ac^+ non-ETEC strains. Gross pathology observations revealed catarrhal and desquamative enteritis in 3/5 M1823-infected pigs, and only a mild inflammation of the small intestine in 1/5 1466- and 2407-inoculated pigs. Electron microscopy showed lesions produced by attaching-effacing bacteria in the jejunum of 3/5 M1823- and 1/5 1466-infected pigs. We suggest that non-ETEC strain 2407, containing recombinant plasmid pMK005 that encodes F4ac fimbriae, could be used as a source of the replicating antigen required for development of oral vaccine to protect against postweaning ETEC infections in pigs.

Attaching-effacing activity; adherent; non-toxigenic E. coli; pigs.

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