CsrA and CsrB are required for the post-transcriptional control of the virulence-associated effector protein AvrA of Salmonella enterica.

The virulence-associated effector protein AvrA of Salmonella enterica is an ubiquitin-like acetyltransferase/cysteine protease, which interferes with the first line of immune response of the target organism. In contrast to translation of the AvrA protein in S. enterica strains, which takes place either constitutively (class 1 strains), or after acid induction (class 2 strains), or not at all (class 3 strains); the constitutive transcription of the respective avrA genes occurs regardless of these defined expression classes.

The expression of the virulence-associated effector protein gene avrA is dependent on a Salmonella enterica-specific regulatory function.

Although the avrA gene is prevalent among 80% of the Salmonella enterica serovars, only a small number of them usually express the respective virulence-associated effector protein AvrA. However, under culture conditions below pH 6.0 many of the AvrA non-producer strains (e.

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

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.

Molecular properties of Salmonella enterica serotype paratyphi B distinguish between its systemic and its enteric pathovars.

Salmonella enterica serotype O1,4,5,12:Hb:1,2, designated according to the current Kauffmann-White scheme as S. enterica serotype Paratyphi B, is a very diverse serotype with respect to its clinical and microbiological properties. PCR and blot techniques, which identify the presence, polymorphism, and expression of various effector protein genes, help to distinguish between strains with systemic and enteric outcomes of disease.