Prevalence and polymorphism of genes encoding translocated effector proteins among clinical isolates of Salmonella enterica

Pathogenic Salmonella enterica strains are capable of causing local and/or systemic infections. They employ two type III secretion systems to transloc ate an array of virulence-associated proteins (effector proteins) directly into the cytosol of target cells of the host. Earlier data had shown that c hanges in the repertoire of translocated effector proteins may contribute t o the adaptation of Salmonella strains to new hosts and to the emergence of epidemic strains. Using PCR and Southern blot techniques the presence of a nd the polymorphism among the genes encoding the translocated effector prot eins SopB, SopD, SopE, SopE2, SipA, SipB, SipC, AvrA, and SptP was studied in 71 phylogenetically well characterised S. enterica subspecies I (subspec ies enterica) strains of the SARB collection and in 209 clinical and epidem ic isolates of S. enterica subspecies I belonging to various serovars, phag e types, and genotypes. fill these Salmonella strains harbour ail these res pective genes with the exception of sopE and avrA which have been identifie d in only some of them. Several of the studied genes display genetic polymo rphisms (RFLP). These RFLP patterns did not show a strict correlation with the genetic distance, the grouping genes in order to understand their role in the evolution of Salmonella as a pathogen.