Methionine sulfoxide reductase (msr) gene deletion strains of Salmonella Typhimurium in poultry

Salmonella encounters but survives host inflammatory response. To defend host-generated oxidants, Salmonella encodes primary antioxidants and protein repair enzymes. Methionine (Met) residues are highly prone to oxidation and convert into methionine sulfoxide (Met-SO) which compromises protein functions and subsequently cellular survival. However, by reducing Met-SO to Met, methionine sulfoxide reductases (Msrs) enhance cellular survival under stress conditions. We created mutant strains by deleting msrA, msrB, msrC, msrP and bisC and named delta five msr (involves deletion of five msr genes) and delta four msr (involves deletion of four msr genes).