Epidemiological Survey On The Infection Of Hepatitis E Virus Among Pigs In Partial Regions Of China

HEV is a non-enveloped virus, with a positive-sense, single-stranded RNAgenome.It is primarily transmitted by the fecal-oral route and causes sporadic and epidemichepatitis E. Hepatitis E has mainly occured in developing countries, especially withpoor sanition. As sensitive animal reservoir, pigs act as an important role in thetransmission of HEV. Therefore, it's very important to understand the status of swineHEV infections in some regions of China in order to take measures for avoidingtransmission of HEVvia domestic animals.We collected 3346 serum samples of pigs from Hunan, Hubei and Henan regions ofChina. The anti-HEV antibody and HEV antigen in those samples were detected byusing ELISA. The results showed that 2741 of 3346 (81.92%) and 308 of 3346 (9.21%)were positive for swine HEV antibody and antigen respectively. The highest positiverates of anti-HEV antibody and antigen were 100% and 37.50% respectively in thedifferent regions. The positive rates of anti-HEV antibody and antigen were significantdifferent among the 3 regions (P<0.01). The positive rate for anti-HEV antibody andthe ratio of anti-HEV antibody with higher titer in pigs with more than 3 months weresignificant higher than those in pigs with less than 3 months whilst the positive rate ofHEV antigen was significant lower than that in pigs with less than 3 months. On thebase of serological analysis, we tested 1314 serum samples of pigs that were positivefor HEV antigen and with S/CO≤10 for antibody using real-time RT-PCR. The resultsshowed that 64 of 1314 samples were positive for swine HEV RNA, and 50 of the 64samples were positive for HEV antigen. Using the nested RT-PCR assay to detect the64 samples, we obtained 32 PCR products. They were sequenced and compared toeach other as well as to other known human, swine strains of HEV. Sequence analysesrevealed that 3 isolates belong to HEV genotype 1 and 29 isolates belong to HEV genotype 4 including 14 isolates that didn't belong to any reported subtype of HEVgenotype 4. The results indicate that the infection rate of HEV in pigs is high althoughit is significant different among regions. The main genotype which pigs infected inChina is HEVgenotype 4.