Immunization of human hepatitis E viruses conferred protection against challenge by a camel hepatitis E virus.

Dromedary camel hepatitis E virus is a novel HEV that belongs to the family Hepeviridae, and is classified as genotype 7 HEV (HEV-7). Since HEV-7 is transmitted from camels to humans and causes acute hepatitis E, this virus is a non-negligible pathogen for zoonosis, and a vaccine against HEV-7 infection is urgently needed. Here, we first intravenously inoculated HEV-7 to rhesus monkeys to explore the susceptibility, and we established an animal model. We then used virus-like particles (VLPs) of HEV-1 (HEV-1 VLPs) and HEV-3 (HEV-3 VLPs), a candidate hepatitis E vaccine, to intramuscularly inoculate rhesus monkeys. The monkeys elicited IgG antibody titers as high as >1:102,400 against heterologous HEV-7 without any adjuvants. The HEV-1 VLPs and HEV-3 VLPs-immunized monkeys were challenged intravenously with HEV-7, and they were protected completely from the infection, demonstrating that these VLPs could be a usable vaccine against HEV-7 infection. We also observed that HEV-7-infected rhesus monkeys did not show any liver damage during these experiments. Further efforts are necessary to establish an animal model for investigation of the pathogenesis of hepatitis E caused by HEV-7 infection.