Seroprevalence of hepatitis E virus (HEV) in Western Cape, South Africa

Genotyping and subtyping are important to understand epidemiology of the hepatitis E virus so as to improve control measures to prevent transmission of virus in the community. Hence, the aim of the current study was to identify the prevalent HEV genotypes in Eastern India in acute sporadic hepatitis E cases with varying degree of liver failure. The study was carried out in Calcutta Medical College, Kolkata, a tertiary care centre in West Bengal from Aug, 2012 to Nov, 2014. The study was approved by the institutional ethics committee. On the basis of disease severity the study comprised two HEV-induced groups: acute viral hepatitis (AVH) and acute liver failure (ALF), respectively. Samples were tested for hepatitis B virus (HBV) surface antigen, anti-hepatitis C virus antibodies, anti-hepatitis A virus IgM, anti-HEV antibodies (IgM and IgG) by ELISA. Of the 285 patients with acute hepatitis, 117 (41.05%) were positive for HEV either alone (n = 98) or in combination with another hepatotropic virus by serology. Among these 117 patients, 70 had AVH and 47 developed acute liver failure during the course of infection. There was no mortality among the 70 AVH patients, while seven patients (14.9%) with acute liver failure died. Serum samples from 42 acute sporadic hepatitis cases (within 7 days of illness and negative for all serological markers) were investigated for the presence of HEV RNA by nested polymerase chain reaction (RTnPCR) using primers designed with in RdRp (RNA dependent RNA polymerase) region of open reading frame-1 (ORF-1). Seventeen patients (10 AVH, 7 ALF) found to be positive for HEV RNA were sequenced by direct sequencing on ABI prism 310. The sequences (343 nucleotides) were compared with each other and were aligned with previously reported HEV sequences obtained from GeneBank, using Clustal W software. A Phylogenetic tree was constructed by using PHYLIP version 3.67 software. The sequences of these 17 HEV isolates shared 91.3–98.5% sequence homology among themselves. All AVH and only two ALF isolates belonged to genotype 1a and the remaining 5 ALF isolates were clustered with genotype 1c. HEV isolates which belonged to genotype 1a had 91.5–94.2% homology with subtype 1a and HEV isolates which belonged to genotype 1c had 90.1–93.5% homology with subtype 1c. There was a high degree of variability between genotypes 3 and 4, with a divergence of 31.2% and 30.1%, respectively. Patients with genotype 1c had significantly higher alanine aminotransferase levels (median 2930 IU/L, 1837–3763 versus 1324 IU/L, 945–2317; p = 0.01) than genotype 1a and prothrombin time was lower in the genotype 1c patients (median 61% versus 84%; p = 0.05). This is the first study from Eastern India reported genotype 1 in humans with subgroup ‘a’ and ‘c.’ Interestingly, we observed that the patients with genotype 1c tend to have more clinical manifestation than those with genotype 1a infection.