Hepatitis E Virus in Macaca Mulatta Huang F et al. 747 Figure 1. Phylogenetic Analysis Based on the ORF2 (350 bp) Sequence of the Isolates in This Study and 25 Other References of 4 HEV Genotypes, Using the Neigh- bor-Joining Method The tree was evaluated using the interior branch test method with Mega 4 software. Percent bootstrap support (greater than 70%) is indicated at each node. The scale bar represents nucleotide substitutions per base. GenBank accession no., country of origin, and species are indicated. The isolates identiﬁed in this study are marked with a triangle. of females were positive for anti-HEV IgG antibodies, but only 24% (12/50) of males tested positive (Table 1). The rate of anti-HEV IgG antibody detection was signiﬁcantly higher in females than in males (P > 0.01), which sug- gested that females may be more sensitive to HEV infec- tion than males. No signiﬁcant diﬀerences were found in the rate of infection in diﬀerent age groups, with 41.25% of adolescents testing positive (age, 1 to 4 years), 31.25% of adults testing positive (age, 5 to 20 years), and 40% of el- ders testing positive (age, greater than 20 years, Table 1). 4.2. Detection of HEV RNA HEV RNA was detected by RT-nPCR. The HEV positive rate was 2.5% (4/162) in swine stool samples; however, we failed to detect HEV RNA both in stool and serum samples for Macaca mulatta. 4.3. Phylogenetic Analysis The 4 swine HEV strains isolated from the village were highly homologous (98.3–99.4%), and shared high similarity (98%) with the strain isolated from a slaugh- terhouse in the city of Kunming last year (GenBank: HQ828103, Figure 1). These swine strains share 97% simi- larity with the strain isolated from Xinjiang province in 2009 (GenBank: GU119961), and 96% similarity with the Wuhan isolate (GenBank: GU188851), also from 2009. Phylogenetic analysis suggested that swine HEV strains prevalent in China have remained highly conserved in recent years. When compared with the reference HEV iso- lates, homology was above 79% for genotype 1 (GenBank: M80581), 80% for genotype 2 (GenBank: M74506), 77% for genotype 3 (GenBank: AY575857), and 94% for genotype 4 (GenBank: EU034709). One of the sequences in this study was submitted to GenBank (JF747598). Phylogenetic analysis clearly illustrated that all HEV Hepat Mon. 2011;11(9):745-749