748 Huang F et al. sequences could be divided into 4 distinct genotypes, as was found in previous studies (14, 15). The HEV sequences isolated in the present study clearly belonged to geno- type 4 and formed a cluster together with the Kunming, Xinjiang, and Wuhan strains (Figure 1). 5. Discussion Pigs serve as an important reservoir for HEV, and expo- sure to pigs may pose a risk of zoonotic infection. Wild rhesus macaques captured from the rural region of the Yunnan province quite often come in contact with both pigs and humans. Although Macaca mulatta has been frequently inoculated (either orally or intravenously) with human, swine or avian HEV strains to serve as ani- mal models in HEV studies, whether it generally carries anti-HEV antibodies or HEV RNA has remained unknown. The present study provided data to describe the seroepi- demiology of HEV in Macaca mulatta and the molecular characterization of HEV in pigs in the Yunnan province of China from samples collected between 2008 and 2011. Al- though the percentage of rhesus macaques testing posi- tive for anti-HEV IgG antibodies (35.87%) was lower than that of wild rats (44–90%, (7)) or pigs (66.4–81.6%, (16, 17)), it was higher than that of humans (21.1%, (14, 16)), cattle (18.7%), and sheep (12.4%) (16). The prevalence of anti-HEV IgG antibody suggested that Macaca mulatta may be fre- quently exposed to an HEV-like antigen, as is observed in dogs, rats, and cats (8, 18). Few rhesus macaques (0.44%, 3/92) were positive for HEV IgM, which indicated that the HEV-like antigen was still prevalent in this area. However, we failed to detect HEV RNA in both serum and stool sam- ples from these macaques by a universal RT-PCR assay that is capable of detecting genetically divergent strains of HEV. Swine HEV strains prevalent in this area were highly conserved throughout most of the swine HEV strains in China. However, only 2.5% of pigs tested in this study were positive for HEV RNA, a value much lower than that seen in other provinces in China, such as Shanghai (7%, 39/554, (19)) and Beijing (22.89%, 19/83, (20)). Phylogenet- ic analysis revealed that the HEV isolate from this study clustered with the Chinese swine HEV strains but were distinct from Japanese strains of human HEV and most strains of swine HEV from other countries. The most prevalent viruses are the genetically diverse genotype 4 viruses, and the HEV strains isolated from diﬀerent geo- graphic regions of the world are genetically heterogenic. The monkeys sampled in this study were originally cap- tured from the wild, suggesting that HEV infection might have been acquired from contact with HEV-infected wild boars, wild rats, or humans. 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