[Model of chronic salmonellosis: parameters of infection and immune response in inbred mice genetically variable in susceptibility to salmonellosis].

AIM

Study parameters of chronic infection and immune response in I/St and A/Sn line mice in the model of per oral infection of mice with Salmonella enterica serovar Typhimurium.

MATERIALS AND METHODS

Studies were carried out in I/StSnEgYCit (I/St), A/JsnYCit (A/Sn) inbred line mice as well as their back crossing hybrids [I/StrxF1(I/StxA/Sn)]BC. Mice were infected per os by S. enterica serovar Typhimurium strain IE147 at a dose of 2 x 10(5) PFU per mice. The number of salmonellae was determined at days 3, 5 and 7, weeks 3 and 4 after the infection in various organs, the number of antibody producers--by cell EIA. Pathomorphologic changes in mice spleens were studied histologically by using hematoxylin and eosin staining. In offspring of back crossing [I/St x F1(I/St x A/Sn)]BCl segregation genetic analysis of sensitivity to salmonella infection trait and mapping of loci taking part in salmonella infection were carried out.

RESULTS

The course of chronic salmonellosis in susceptible I/St line was characterized by the presence of more pronounced pathomorphologic changes in spleen and significantly higher microbial load in organs (approximately by 1000 times) when compared with A/Sn mice. Interlinear differences in susceptibility to infection correlated with differences in the type of early local and systemic immune response. In I/St mice a higher level of salmonella specific IgG2a-, IgG1- and IgA forming cells in spleen compared with A/Sn mice was detected which correlates with a pronounced splenomegaly and high concentration of salmonellae. On the contrary A/Sn mice demonstrated a higher level of salmonella specific IgA forming cells in Peyer patches that probably leads to protection of A/Sn line during per oral infection. Genetic analysis of susceptibility to salmonellosis trait inheritance showed the presence of its coupling with D9Mit89 locus of chromosome 9 on which previously Tbs2 locus was mapped that plays a role in the control of tuberculosis infection.

CONCLUSION

There is a probability of the presence of general mechanisms of genetic control of tuberculosis and salmonella infections in A/Sn and I/St mice.