Salmonella enterica serovar Typhimurium strains of requencing

Salmonella enterica serovar Typhimurium (S. Typhimurium), exhibiting a broad range of hosts, is the major cause of gastroenteritis in human. However, the S. Typhimurium variant ST313 strain has emerged in sub-Saharan Africa and may cause invasive disease that presents as a febrile systemic illness in adults and children with 20%-25% of fatality rate. Thus, it is necessary to investigate the interaction between different S. Typhimurium strains and host. Here, we respectively infected C57BL/6 mice with different original S. Typhimurium strains SL1344 (calf), CVCC541 (chicken) and CMCC50115 (mutton) to determine the differential virulence and host immune response to three strains infection. The results showed that CVCC541 and CMCC50115 strains were attenuated strains compared to SL1344 by the detection of susceptibility of mice to three strains. At 3 days after infection, CVCC541 and CMCC50115 strains enhanced host innate immunity by the increased frequencies of macrophages and neutrophils. Reversely, SL1344 strain evaded immune response by the induction of apoptosis of macrophages. Moreover, CVCC541 strain elicited the adaptive immunity after 11 days of infection when the proliferation and activation of CD4+ T cells were evaluated by Flow cytometry. In addition, 125 and 138 unique functional mutant genes in CVCC541 and CMCC50115 strains respectively and 78 shared mutant genes were annotated by genomic alignment to SL1344 strain and the signal pathways that these genes involved in were analyzed. All these results indicated that different original S. Typhimurium strains showed differential virulence and induced diverse immunity in the same host infected.