The Infectivity Of Dromedary Camel Hepatitis E Virus(DcHEV) In Rhesus Monkey And The Analysis The Immunogenicity Of Virus-like Particles

Hepatitis E is viral hepatitis caused by hepatitis E virus(HEV)infection.HEV is mainly transmitted through fecal-oral route.Up to now,at least five genotypes of HEV have been shown to infect humans and cause hepatitis E.Hepatitis E is not only occurs in developed countries,but also frequently occurs in developed nations.Hepatitis E is one of the common infectious diseases and aroused global attention.Dromedary camel hepatitis E virus(DcHEV)is a newly-discovered HEV,which infects both dromedary and humans.However,due to DcHEV hasn't been discovered for a long period,the pathogenicity,replication mechanism and epidemic status of DcHEV are still unclear.Relevant animal experiments and studies are also inadequate and whether the existing HEV vaccine can protect DcHEV infection is also unknown.In this study,we examine the infectivity of DcHEV in rhesus monkey and use rhesus monkey as animal model to analyze immunogenicity of hepatitis E virus-like particles(HEV-LPs),and evaluate the possibility for vaccine development.The results were as follows:1.The rhesus monkey is susceptibility to DcHEV infection:DcHEV was recovered from cell culture supernatants.Three rhesus monkeys were inoculated intravenously with 2.5x106 copies,5x106 copies and 107 copies of DcHEV,respectively.Fecal and serum samples were collected for detection of DcHEV-RNA by real time RT-PCR.The anti-HEV IgG,IgM in serum detected by ELISA.ALT and AST were tested to evaluate the liver damage.The observation period is 10 weeks.After inoculation the DcHEV RNA were detected in both fecal and serum,also the HEV IgG and IgM antibodies were detected in the serum,it showed that the rhesus monkey susceptible to DcHEV infection and the rhesus monkey could be use as the animal model for DcHEV infection.Furthermore,it also showed that the DcHEV not only infect camels but also cross-species infects primates.2.Immunogenicity of hepatitis E virus like particles(HEV-LPS)and its clinical protective effects on DCHEV infected rhesus monkeys:2.1.Anti-HEV IgG antibody produced by immunized with G1 HEV-LPs and G3 HEV-LPs.Each three rhesus monkeys were inoculated G1 HEV-LPs or G3 HEV-LPs through intramuscular injection on days 0,16 and 30.All of the inoculations were carried out without adjuvant.Serum samples were collected on days 0,16,30 before the injection and days 39 post inoculation.Anti-HEV IgG titers were detected by ELISA.Although without any adjuvants,after three time inoculation,anti-HEV IgG was detected in all of six monkeys with titers higher than 1:102,400.This result showed that the G1 and G3 HEV-LPs induced strong immune response in rhesus monkeys.2.2 Immunized rhesus monkeys were protected from DcHEV infection.Six HEV-LPs immunized rhesus monkeys and two naive rhesus monkeys were intravenously inoculated with DcHEV(106 copies).The serum samples were collected and used for the detection of DcHEV RNA,anti-DcHEV IgG and ALT values.Fecal were collected for detection of DcHEV RNA.After inoculation the DcHEV RNA in the serum and fecal was detected and the anti-HEV IgG elicited in two naive monkeys,it showed that the DcHEV recovered from the monkey is infectious.In contrast to the naive monkeys,no DcHEV RNA was detected in rhesus monkeys positive for anti-HEV IgG.No significant elevation of ALT was observed in all of these 8 monkeys.These results indicated that anti-HEV antibodies elicited by immunized with G1 and G3 HEV-LPs was capable of protecting monkeys from DcHEV infection.The present study demonstrated that the rhesus monkey is susceptible to DcHEV infection and could be used as animal model for DcHEV cross species infection and hepatitis E vaccine evaluation.Anti-HEV IgG antibody was induced by imunized with G1 and G3 HEV-LPs and protected rhesus monkeys from DcHEV infection suggesting that HEV-LPs can be a candidate for the hepatitis E vaccine.