Expression profiles of effector proteins SopB, SopD1, SopE1, and AvrA differ with systemic, enteric, and epidemic strains of Salmonella enterica

Abstract

The presence and expression of sopB, sopD1, sopE1, and avrA genes encoding virulence associated effector proteins were studied comparatively in 405 Salmonella enterica strains. They belong to different serovars and clonal types (genotypes, phage types) and originated from different clinical (systemic infection, focal enteritis, enterocolitis) and epidemic sources (epidemics, sporadic cases). The sopB and sopD1 determinants were commonly prevalent, but sopE1 and avrA genes only in 55% and 80%, respectively. A correlation of this pattern of absence and presence of the respective genes to the epidemic and clinical origin could not be detected. In contrast, the expression of the respective genes appeared differently: SopB and SopE1 proteins are well produced, but SopD1 and AvrA proteins only rarely under the applied standard culture conditions. However, using a range of different environmental signals (temperature, pH, cations, etc.) some of the S. enterica nonproducer strains (e. g., S. Agona, S. Bovismorbificans, S. Virchow, etc.) begin to produce AvrA and SopD1. They turned now into an expression profile which was found typically for the epidemic strains of S. Typhimurium and S. Enteritidis. Also S. enterica strains from systemic infections could be characterized by their strong SopB and SopE1 expression while SopD1 and AvrA proteins were missing. Although it is premature to outline generally a correlation of these expression profiles and the clinical and epidemiological potency of Salmonellae, the reported results allow a first understanding how a fine tuning of their virulence will take place.

Virulotyping of Salmonella enterica subsp. enterica isolated from indigenous vegetables and poultry meat in Malaysia using multiplex-PCR

“…The results from this study are in agreement with Streckel et al (2004) and Hughes et al (2008) who found a low prevalence of the sopE gene in S. enterica. SopE is encoded by a P2-like cryptic bacteriophage (SopEA) (Hardt et al 1998).…”

SipA, SopA, SopB, SopD and SopE2 effector proteins of Salmonella enterica serovar Typhimurium are synthesized at late stages of infection in mice

“…The whole avrA gene plus 300 nt downstream were sequenced in strain SSM 3215, confirming the correct fusion of the ORF with the 36FLAG coding sequence. It is worth pointing out here that the avrA gene is present in approximately 80 % of S. enterica serovars, although few of them synthesize the effector (Streckel et al, 2004).…”

“…Interestingly, the avrA gene is prevalent in the majority of S. enterica serovars; however, only a small number of them usually produce the protein (Streckel et al, 2004). Ben-Barak et al (2006) have demonstrated that avrA expression is dependent on a specific regulatory function which appears to be differently modulated in the distinct Salmonella serovars.…”

“…In our in vitro experiments, the lack of AvrA detection is remarkable, and might be due to nonpermissive expression conditions in our standard culture procedure. Indeed, Streckel et al (2004) have shown that some of the non-producer strains begin to produce AvrA in low-pH culture. On the other hand, the failure in the detection of AvrA in vivo is in agreement with the report of Lawley et al (2006), who show that the avrA gene product lacks of an obvious role during long-term systemic infection; AvrA must be regarded as an effector protein involved in the enteritis pathway.…”

Salmonella Effector AvrA Regulation of Colonic Epithelial Cell Inflammation by Deubiquitination

“…Recently studies showed that the AvrA gene is present in 80% of Salmonella enterica serovar. 1 Although its exact function is not entirely clear, AvrA belongs to the family of cysteine proteases regulating diverse bacterialhost interactions. 2 Other family members related to AvrA include the adenovirus protease AVP, Yersinia virulence factor YopJ (Yersinia outer protein J), and the Xanthomonas campestris pv.…”