ROLE OF SEFA SUBUNIT PROTEIN OF SEF14 FIMBRIAE IN THE PATHOGENESIS OFSALMONELLA-ENTERICA SEROVAR ENTERITIDIS

In this study, the role of the SefA subunit protein of SEF14 fimbriae in the pathogenesis of Salmonella enterica serovar Enteritidis was inv estigated. This was accomplished by mutating the sefA gene in the chro mosome of two strains of S. enterica serovar Enteritidis by allelic ex change with a copy that has been inactivated by interruption with a no npolar kanamycin resistance (aphA-3) cassette. The effect of this muta tion on the ability of the S. enter ica serovar Enteritidis strains to colonize the intestinal epithelium and to invade other tissues was as sessed in BALB/c mice and in vitro by adherence and invasion of HeLa c ells. Our results show that an avirulent S. enterica serovar Enteritid is vaccine strain, 11RX (no somatic antigen; flagellum antigen phase 1 , g,m; flagellum antigen phase 2, -), colonized be better and persiste d longer in the Peyer's patches of these mice than did its SefA-defici ent counterpart. However, no such difference was observed between a hi ghly virulent S. enterica serovar Enteritidis strain, 7314 (somatic an tigen, O1, O9, O12; flagellum antigen phase 1, g,m; flagellum antigen phase 2 [1,7]), and its SefA-deficient isogenic mutant. These findings were correlated with in vitro adherence and invasion of HeLa cells. F urthermore, we could not demonstrate a role for SefA in the virulence of S. enterica serovar Enteritidis as assessed by 50% lethal dose dete rminations. The implications of these findings are discussed.