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Abstract: Abstract background: Helicobacter pylori (H. pylori) is a major human pathogen that is responsible for various gastroduodenal diseases. We investigated the prevalence of H. pylori virulence markers in a region at high risk of gastric cancer. Methods: One hundred and sixteen H. pylori strains were isolated from patients with gastroduodenal diseases. cagA, the cagA 3′ variable region, cagPAI genes, vacA, and dupA genotypes were determined by PCR, and some amplicons of the cagA 3′ variable region, cagPAI genes and dupA were sequenced. Results: cagA was detected in all strains. The cagA 3′ variable region of 85 strains (73.3%) was amplified, and the sequences of 24 strains were obtained including 22 strains possessing the East Asian-type. The partial cagPAI presented at a higher frequency in chronic gastritis (44.4%) than that of the severe clinical outcomes (9.7%, p < 0.001). The most prevalent vacA genotypes were s1a/m2 (48.3%) and s1c/m2 (13.8%). Thirty-six strains (31.0%) possessed dupA and sequencing of dupA revealed an ORF of 2449-bp. The prevalence of dupA was significantly higher in strains from patients with the severe clinical outcomes (40.3%) than that from chronic gastritis (20.4%, p = 0.02). Conclusion: The high rate of East Asian-type cagA, intact cagPAI, virulent vacA genotypes, and the intact long-type dupA may underlie the high risk of gastric cancer in the region. [Copyright &y& Elsevier]

Abstract: Streptococcus suis is an important swine pathogen responsible for a diverse range of diseases. S. suis serotype 2 (SS2) and S. suis serotype 9 (SS9) are the prevalent serotypes in diseased Chinese pigs. Little is known about SS9 virulence factors. Two strains, GZ0565 and SH040917, were isolated from a diseased pig and a healthy pig, respectively. Suppression subtractive hybridization (SSH) was used to identify SS9 virulence genes associated with pathogenicity. We identified 30 gene fragments unique to GZ0565, including stp which encodes a serine/threonine protein phosphatase known to affect the virulence and morphology of bacteria. To investigate the role of stp in pathogenesis of SS9, an isogenic stp mutant (Δstp) and a complementation strain (CΔstp) were constructed. The results demonstrated that the stp affected the expression of a few genes involving in adhesion and virulence for bacteria. The Δstp exhibited a significant decrease in HEp-2 cell adherence, compared with the wild type, and a reduced survival ratio in whole blood. The Δstp was attenuated in a CD1 murine model of infection and its LD50 values was seven-fold higher than the wild type. Our data suggest that stp is involved in the pathogenesis of SS9. [Copyright &y& Elsevier]