Analysis of complete genome sequences of swine hepatitis E virus and possible risk factors for transmission of HEV to humans in Korea

Abstract

The hepatitis E virus (HEV) is an emerging zoonotic agent, for which pigs are the most important reservoir. Complete genome sequences of two swine HEV strains, designated swKOR-1 and swKOR-2, were determined via RT-PCR and RACE-PCR. The strains contained genomes composed of 7,222- and 7,221-bp excluding the poly(A) tails, respectively. The swKOR-1 and swKOR-2 strains were classified into subtype 3a of genotype 3 via phylogenetic analysis. These strains formed a distinctive cluster in the phylogenetic tree with human and swine HEVs isolated in the USA and human HEVs isolated in Japan. Anti-HEV antibodies were identified via ELISA in 8 of 99 (8.1%) cats, whereas, among 115 cattle and 213 dogs, no HEV-specific antibodies were detected. The conserved RNA-dependent RNA polymerase (RdRp) gene of HEV could be detected via RT-PCR in 8.7% of raw oysters collected from coastal regions in Korea. The HEV RNAs detected in oysters were identified as belonging to subtype 3a. The HEV RNAs in oysters most closely resembled that of the swKOR-2 strain. They also showed a close genetic relationship with the swKOR-1 strain and the swine and human HEVs isolated in the USA. This is the first report describing the detection in oysters of HEV that may have originated from genotype 3 swine HEV in Korea. Pigs and cats infected with HEV, as well as oysters contaminated with HEV, are potential risk factors for HEV transmission to humans.

Bioaccumulation Efficiency, Tissue Distribution, and Environmental Occurrence of Hepatitis E Virus in Bivalve Shellfish from France

“…The large variation observed for oysters was due to a high value in July (allometric coefficient of 22). For clams, the allometric coefficients in January and March (10 and 9) were lower than those obtained in the 3 other experiments (14,16,18). For the 2 other species, low variability was observed.…”

“…For example, HEV was detected in Italian mussels that were being utilized as bioindicators of marine pollution (11) and in marketplace mussels in Spain (49). In Thailand, none of 213 samples analyzed were found to be positive for HEV (50), and in Korea, about 9% of 161 oyster samples were positive (14).…”

“…A large variety of human enteric viruses have been detected in different shellfish species during either environmental studies or outbreak investigations (9,10). HEV has been reported in shellfish collected in different European and Asian countries (11)(12)(13)(14). Few outbreaks have been reported until now.…”

A nationwide survey of hepatitis E viral infection in French blood donors

“…That is probably why eating seafood has been found to be associated with the presence of anti-HEV IgG and why the HEV genome has been identified in oysters-they are grown mainly in estuaries. (40) This could well explain why we found that eating oysters was linked to the presence of IgG.…”

Prevalence of antibodies against hepatitis E virus in wild boars (Sus scrofa) in Korea

“…Therefore, a number of epidemiological studies have been conducted on domestic and wild swine populations to determine the prevalence of HEV infection worldwide (de Deus et al, 2008;Kaba et al, 2010;Martelli et al, 2008;Rueter et al, 2009;Schielke et al, 2009, Takahashi et al, 2014. Previous serological studies performed on human, pig, and cat populations in Korea reported an 18%, 15%, and 8.1% prevalence of anti-HEV antibodies (Choi et al, 2003;Song et al, 2010). Moreover, anti-HEV antibodies were detected in 14 of 64 zoo animal species at different ratios (Song et al, 2013).…”