我国戊型肝炎研究

Studies on hepatitis E in China

An epidemic of hepatitis in the south part of Xinjiang Uighur Autonomous Reg ion during 1986-1988, and 2 548 acute sporadic hepatitis cases from 17 cities of Ch i na were studied. The disease had following clinical and epidemiological char acte ristics: 86.4% cases occurred in the age group of 20-59 years; with male prepon d erance and autumn-winter excess; 75% patients had a history of contact with hep a titis cases, and / or eating out or drinking unboiled water; clinical features w ere s imilar to hepatitis A, with a higher fatality rate, especially in pregnant women (up to 21%). Two strains of hepatitis E virus (HEV) isolated from Xinjiang were completely seq uenced by dideoxy chain termina tion method, with nucleotide homology of 93.5% and 94.5% with Burma strain (geno type 1), 75.7% and 75.9% with Mexico strain (genotype 2), 73.7% and 74.2 % with American strain (genotype 3), respectively. It suggests that these two st rains belong to genotype 1. The partial sequencing of open reading frame (ORF)2 region of 98 HEV isol ates from 19 cities of China revealed that 62 of them (63.3%) shared the same ge notype with Burma and Xinjiang strains, and 36 (36.7%) isolates were of genotype 4. One of the 36 strains was completely sequenced, with nucleotide identity of 75% with Burma strain, 74.5% with Mexico strain and 75.3% with American strain , respectively. Sera collected from 419 pigs, 190 cattle and 316 goats from var ious regions of China were detected for anti-HEV antibodies and HEV RNA using a n in-house enzyme immunoassay (EIA) and reverse transcriptase nested polymerase chain re action (RT-nPCR) with primers from ORF 2. The mean positivity rates of anti-HEV antibody for pigs and cattle were 78.8% and 6. 3%, respectively, but none of the goat sera was anti-HEV positive. The PCR product s (nt 6007- 6354) of 5 HEV RNA positive sera were sequenced and compared to othe r HEV sequences in the nucleotide databases. The five sequences shared 74%-79%, 73%-74%, 73%-78%, and 83%-99% identity to HEV genotypes 1,2,3 and 4, respe c tively. An enzyme immunoassay (EIA) and Western immunobloting (WB) for detection of anti-HEV and a reverse transcriptase nested polymerase chain reaction (RT- nPCR) of HEV RNA were developed. The anti-HEV EIA kit was approved by the State Drug Administration, China. An experimental model of HEV was established in rhe sus monkeys (Macaca mulatta). The animal studies on HEV cDNA vaccine and recombi nant vaccine showed that the humoral immune response to HEV was induced in mice after inoculation of the HEV RNA vaccine, and the HEV recombinant vaccine provid ed a protection from HEV infection in Rhesus monkeys.