Near full-length genome analysis of HEV 4b subtype in pigs showed a similarity up to 99.944% compared to a patient in Guangdong province, China.

Hepatitis E virus (HEV) is a prevalent pathogen responsible for acute viral hepatitis, HEV genotypes 3 and 4 infections causing zoonotic infections. Currently, the nucleotide similarity analysis between humans and pigs for HEV genotype 4 is limited. In this study, stool samples from an HEV-infected patient who is a pig farmer and from pigs were collected to obtain the near full-length genome of HEV, phylogenetic trees were constructed for genotyping, and similarity of HEV sequences was analyzed. The results showed that HEV-RNA was detected in the stool samples from the patient and six pigs (6/30, 20.0%). Both HEV subtype in the patient and pigs was 4b. Additionally, similarity analysis showed that the range was 99.875%-99.944% between the patient and pigs at the nucleotide level. Four isolates of amino acid sequences (ORFs 1-3) from pigs were 100% identical to the patient. Phylogenetic tree and similarity analysis of an additional nine HEV sequences isolated from other patients in this region showed that the HEV sequence from the pig farmer had the closest relationship with the pigs from his farm rather than other sources of infection in this region. This study provides indirect evidences for HEV subtype 4b can be transmitted from pigs to humans at the nucleotide level. Further research is needed to explore the characteristics of different HEV subtypes.

Characterization of cytotoxic Citrobacter braakii isolated from human stomach.

Citrobacter braakii (C. braakii) is an anaerobic, gram-negative bacterium that has been isolated from the environment, food, and humans. Infection by C. braakii has been associated with acute mucosal inflammation in the intestine, respiratory tract, and urinary tract. However, the pathogenesis of C. braakii in the gastric mucosa has not yet been clarified. In this study, the bacterium was detected in 35.5% (61/172) of patients with chronic gastritis (CG) and was closely associated with the severity of mucosal inflammation. Citrobacter braakii P1 isolated from a patient with CG exhibited urease activity and acid resistance. It contained multiple secretion systems, including a complete type I secretion system (T1SS), T5aSS and T6SS. We then predicted the potential pilus-related adhesins. Citrobacter braakii P1 diffusely adhered to AGS cells and significantly increased lactate dehydrogenase (LDH) release; the adhesion rate and LDH release were much lower in HEp-2 cells. Strain P1 also induced markedly increased mRNA and protein expression of IL-8 and TNF-α in AGS cells, and the fold increase was much higher than that in HEp-2 cells. Our results demonstrate proinflammatory and cytotoxic role of C. braakii in gastric epithelial cells, indicating the bacterium is potentially involved in inducing gastric mucosa inflammation.