Asian Musk Shrew as a Reservoir of Rat Hepatitis E Virus, China

The study, conducted in Zhanjiang City, Guangdong Province, involved the examination of 260 shrews trapped between December 2011 and September 2012. Of the 260 shrews, 147 were from Mazhang District and 113 were from Chikan District. The serum samples from the shrews were tested for the presence of HEV IgG and IgM antibodies using an ELISA based on rat HEV-like particles. The results showed that 27 (10.4%) of the samples were HEV IgG positive, and 12 (4.6%) were HEV IgM positive. The IgG-positive rate was higher for shrews from Mazhang District than for those from Chikan District, with a significant difference (p<0.05). The rates of IgM-positivity did not differ significantly between the two districts. Further analysis of the IgG-positive samples revealed that the sequences were similar to those of HEV isolates from wild rats in the same area. The nucleotide sequences from subcluster A1 and A2 and cluster C rat and shrew strains shared 97.5%–99.6%, 96.8%–97.2%, and 94.0%–97.5% identity, respectively. These results indicate that rat HEV infection occurs in S. murinus shrews and that these rodents are a reservoir for rat HEV. The study also found that the IgG-positive rate among the 6 villages varied substantially, ranging from 8.3% to 71.4%. The IgG-positive rates were 11.6% in male shrews and 9.5% in female shrews, with no statistically significant difference between the sexes. A total of 12 IgM-positive serum samples were selected for HEV RNA testing by nested broad-spectrum reverse transcription PCR, and 5 were positive. Phylogenetic analysis of the 5 HEV isolates indicated that they were all classified into the same group as rat HEV and clearly separated into 2 clusters, A and C. Cluster A isolates were further divided into 2 sub-clusters, sub-A1 and sub-A2. The sequences shared 77.4%–99.6% nucleotide identity with other rat HEV strains, and the sequences from subcluster A1 and A2 and cluster C rat and shrew strains shared 97.5%–99.6%, 96.8%–97.2%, and 94.0%–97.5% identity, respectively. The study suggests that rat HEV may be capable of inducing an immune response in humans, and that understanding the reservoirs of rat HEV is crucial for understanding the epidemiology of HEV in humans. The study was supported in part by the National Major Projects of Major Infectious Disease Control and Prevention, the US Agency for International Development Emerging Pandemic Threats Program, and grants for Research on Emerging and Re-emerging Infectious Diseases, Research on Hepatitis, and Research on Food Safety from the Ministry of Health, Labour and Welfare, Japan.