Epidemiology and genotypes of HEV in Wuhan.

Background: Understanding the genotype and clinical features of the hepatitis E virus (HEV) are important for understanding its characteristics, for evaluating region-specific diagnostic assays, and producing vaccines.

Objectives: To investigate the epidemiology and the genotypes of HEV among outpatients and inpatients in the Department of Infectious Diseases of Tongji Hospital in Wuhan, China.

Methods: Clinical data were elicited from the hospital records of patients who were clinically diagnosed with acute hepatitis between January 2000 and August 2004 (4920 patients). Of these cases, 120 patients with anti-HEV-IgM, IgG-positive were selected to analysis. Conserved genomic sequences of open reading frame 2 (345 bp) in the HEV gene were detected using polymerase chain reaction, 25 of which were cloned and sequenced. Clustal X and Mega software were used for phylogenetic analysis of genotypes strains.

Results: The HEV infection rate is gradually increasing in Wuhan. The number of male patients was 3.3-fold greater than the number of female patients found in clinical investigations. People aged 30-59 years are more susceptible to infection, and people are more susceptible in March-June. Twenty-five isolates shared the same genotype, genotype IV, with 82.61-98.55% nucleotide identity. This genotype had 76.52-81.74%, 70.43-73.04%, 76.52-81.16%, and 84.35-88.70% homology with the nucleotide sequence of HEV genotypes I-IV, respectively. Phylogenetic analysis suggested that these 25 isolates represented at least three different subtypes, but there were no significant differences found in the epidemiological features or liver function of patients with the three subtypes.

Conclusions: HEV sequences isolated from patients in Wuhan belong to different subtypes of HEV genotype IV.