Evaluation of the Correlation between the mRNA Expression Levels of ystA and ymoA Genes in Y. enterocolitica Strains with Different Enterotoxic Properties

Yersinia enterocolitica is one of the main causative agents of human diarrhea. Pigs are a reservoir and the most common source of infection for humans. The aim of this study was to analyze the expression of ystA and ymoA genes in Y. enterocolitica strains with different enterotoxic properties, isolated from humans and pigs. The experiment involved two groups of Y. enterocolitica strains producing and not producing enterotoxin YstA, which were isolated from humans and pigs. All strains were ystA- and ymoA-positive. The expression of ystA and ymoA genes was analyzed by quantitative real-time PCR (qPCR). The relative expression level of the ystA gene was significantly higher than the expression level of the ymoA gene in Y. enterocolitica strains isolated from humans with clinical symptoms of yersiniosis. In other strains, a significant decrease in ystA gene transcription was observed, and the relative expression level of the ymoA gene was significantly higher than the expression level of the ystA gene. Statistically significant differences were not observed in either group of strains isolated from pigs. The results of our study revealed a correlation between mRNA expression levels of ystA and ymoA genes in Y. enterocolitica strains isolated from humans.

Evaluation of virulence genes in Yersinia enterocolitica strains using SYBR Green real-time PCR

Yersinia enterocolitica comprises six biotypes 1A, 1B, 2, 3, 4, and 5. The virulence of the strains belonging to biotypes 1B and 2-5 depends on the presence of both chromosomal and plasmid-borne genes. Strains belonging to biotype 1A do not carry the virulence plasmid pYV. However, they carry other virulence genes, such as ystB and hreP. The aim of this study was to investigate the distribution of yadA, virF, inv, ystA, ystB, myfA, hreP and ymoA virulence genes in Y. enterocolitica strains in order to select the target genes that could be used for the development of a probe-specific real-time PCR to determine the presence of Y. enterocolitica in food samples. A total of 161 Y. enterocolitica strains isolated in eight countries and grouped into biotypes 1A, 2 (serotypes O3, O5 and O9), 3 (serotypes O3 and O9) and 4 (serotype O3) were examined for virulence genes. The most common virulence-associated gene in pathogenic Y. enterocolitica proved to be ystA, which can therefore be considered the best target gene to be amplified in order to evaluate the presence of pathogenic biotypes. By contrast, to identify Y. enterocolitica 1A strains, ystB, which codes for the enterotoxin YstB, can be proposed. This has been found in all non-pathogenic biotypes studied, but never in pathogenic biotypes.