| Hepatitis E virus (HEV), a newly emerged pathogenic microorganism, which was previously classified into the family of Caliciviridae, but is now classfied as Hepevirus genus under the separate family of Hepeviridae by ICTV. It is responsible for the major outbreaks of acute hepatitis in developing countries, especially in tropical and subtropical regions of the world where outbreaks are usually associated with fecal contamination of drinking water. HEV could be superinfected with other Hepeviruses, such as HBV,HDV. Some studies showed, if patients were infected by HBV and HEV simutaneously, the prognosis would be unpredictive. Pregnant women had serious clinical symptoms after being infected by HEV, and the mortality get higher, up to 20%. In short, HE is a kind of communicable disease which casts great shadow on human being's health.Now, We have no HEV vaccine available to implement preventive inoculation among people, and the general positive rate of HEV infection among the whole nation is recognised vaguely, so it is urgent to take all kinds of measures to keep HEV infection under control,such as vaccination. Now, clinically, the diagnosis of HE mainly depended on immunodiagnostics. The efficacy of a certain diagnostic kit could be evaluated by the selection of different antigens. In 1992, a survey has been carried out among 13 provinces and autonomous regions in China to investigate prevalence of HEV using Genelabs EIA kits which had been proved defective later, and the accuracy of results were questioned vastly. In 2005, Lu set up an indirect enzyme-linked immunosorbent assay (ELISA) which was established by using equal concentration of different genotypes and subtypes of HEV p166 recombinant proteins, and consequently verified this mixed antigen more specific, sensitive, pratical than any other antigens.Studies showed that the prevalence of anti-HEV in the south part of China is higher than the north, and Nanjing city is located on the south bank of the Long River in which has the basic conditions for the transmission of HEV because of a lot of water-nets scattering here and there and highly dense popolations. So it is necessary to carry out a survey to clarify the prevalence of anti- HEV in Nanjing area.Until now, single serotype of HEV is recognised, but HEV is a non-enveloped virus in which RNA helicase is located, and liable to mutate due to lacking of rectificatioon enzyme system. The genotype, expressively subgenotype of HEV, evolved by the increase of time.extensive genomic diversity has been observed among HEV isolates. Recently, several classification schemes have been proposed.Several.Amplicons have been rendered by many labs all over the world for the genotyping of HEV, 25 in total,most of which focused on the 5,end of ORF2(nt5994-6294), 5'end of ORF1(nt104-390), 3,end of ORF2(nt 6701-7018). Zhai authenticated that the 3,end of ORF1 (nt4254-4560 MJ-C)is the most feasible region which can substitute the complete genome of HEV for genotyping. Based on his previois work, we used MJ-C to investigate the distribution of HEV genotype or subgenotype in Nanjing region. This research could be divided into two parts.
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