MOUSE SUSCEPTIBILITY TO INFECTION BY THE SALMONELLA-ABORTUSOVIS VACCINE STRAIN RV6 IS CONTROLLED BY THE ITY NRAMP-1 GENE AND INFLUENCES THEANTIBODY BUT NOT THE COMPLEMENT RESPONSES/

Early growth of Salmonella typhimurium in spleen and liver of mice is controlled by the mouse chromosome 1 locus lty/Nramp 1. Genetic contro l of resistance to the attenuated vaccine strain Rv6 of Salmonella abo rtusovis was studied in mice infected by the intravenous route. Compar ison of kinetics of bacterial colonization of spleen and liver in two congenic BALB/c-susceptible (Ity(s)) and -resistant (Ity(r)) mouse lin es showed that BALB/c mice (Ity(s)) were significantly more susceptibl e to infection than C.D2 mice (Ity(r)) suggesting that infection by th is vaccine strain is controlled by a gene which is close or identical to lty/Nramp 1. Congenic mice also differed in their anti-Salmonella a ntibody response, measured by ELISA: susceptible mice had a significan tly higher antibody level than resistant mice, whatever the immunoglob ulin isotype (IgM, IgG1, lgG2a, IgG3, IgA, and total immunoglobulins). The two congenic BALB/c mouse lines had equal serum C3c levels in res ponse to infection. However, we observed a highly significant differen ce according to the sex of mice, suggesting a role of sex hormones in the regulation of the level of some complement factors. These results, obtained with congenic mice, strongly suggest that the Ity/Nramp 1 lo cus controls susceptibility to infection by the S. abortusovis vaccine strain Rv6 and influences the antibody response. (C) 1998 Academic Pr ess Limited.