Determinants of invasion and survival of Yersinia enterocolitica in intestinal tissue. An in vivo study.

The invasion of intestinal tissue by Yersinia enterocolitica was studied after infection of mice with plasmid-bearing or with plasmidless strains of serotype 08 and 03. Within the first 15 h of infection each strain colonized the mouse ileum to the same extent, indicating that the initial binding and invasion are not plasmid dependent. This conclusion is supported by the finding that the plasmidless and the plasmid-bearing Yersiniae (serotype 08) colonize the ileum in a quantitatively similar, dose-dependent manner. The data show that the virulence of Yersiniae depends primarily on their ability to survive and to proliferate within the tissue. This character was expressed by the plasmid-bearing 08 strain, but not by the plasmidless 08 and 03 strain nor by the plasmid-bearing 03 strain. An orally induced rabbit antiserum was used to identify plasmid-coded antigens (relative molecular masses = 47, 45 and 42 kDa), which are expressed in vivo by the plasmid-bearing 08 strain, but not by the three other strains investigated. These antigens may be crucial for virulence of the 08 strain.