No abstract

In the present investigation, a total of 50 stool samples were collected from the food handlers to screen the typhoid asymptomatic carriers, positive result was yielded for 2 out of the 50 samples. Salmonella typhi was isolated and identified based on the cultural characteristics on BSA, Macconkey agar, XLD and phylogenetic analysis. The ompR region of these two strains was amplified, sequenced and a Neighbor-Joining algorithm tree of ompR was constructed. The isolates were designated as (Salmonella Strain) SS-3 and SS-5 respectively. The isolates were subjected to mutation using sodium chloride at various osmolarity concentrations in LB broth. Both the wild and mutant Salmonella typhi were used for the isolation of outer membrane protein. The outer membrane protein was isolated and compared with both the wild and mutated Salmonella typhi. The expression of outer membrane protein was showing the variation in the expression which were noticed by using SDS-PAGE. On the basis of the results, it was concluded that the ompR-envZ two component regulatory systems play an important role on the regulation of Vi polysaccharide synthesis in S. typhi, and that one of the environmental signals for this regulation may be osmolarity.

This study demonstrates that the S. typhi strains were attenuated and could be good vaccine candidates in future.