Abstract
Outer membrane protein YadA, Yersinia adhesin, is one of the plasmid-encoded virulence factors of yersiniae. YadA protects bacteria against host defense through several different mechanisms. One important role of YadA is to mediate binding to several collagen types. Our recent study revealed that a yadA null mutant of Yersinia enterocolitica serotype O:8 has a drastically reduced arthritogenic capacity when injected intravenously into Lewis rats. To further characterize the arthritogenic role of YadA, we repeated the rat experiments with strain Y. enterocolitica O:8/pYV082; this strain expresses a YadA deletion derivative lacking 22 amino acids from the amino-terminal hydrophobic region and does not bind to collagen. Y. enterocolitica O:8/pYV082 induced arthritis in 5 to 14% of rats inoculated with arthritogenic doses, whereas the arthritis incidence with the wild-type parent strain was 65%. The parent strain was slightly more virulent than Y. enterocolitica O:8/pYV082, as determined by rat mortality. It also frequently induced skin abscesses, whereas Y. enterocolitica O:8/pYV082 did not. Infection kinetics in spleen and mesenteric lymph nodes were about the same with both of the bacterial strains used, and the same was true of the Yersinia-specific antibody response. Altogether, these results suggest that YadA-mediated collagen binding contributes to the arthritogenicity of Y. enterocolitica O:8.