Hepatitis E: an overview and recent advances in vaccine research.

Hepatitis E virus (HEV) is an unclassified, small, non-enveloped RNA virus, as a causative agent of acute hepatitis E that is transmitted principally via the fecal-oral route. The virus can cause large water-born epidemics of the disease and sporadic cases as well. Hepatitis E occurs predominantly in developing countries, usually affecting young adults, with a high fatality rate up to 15-20% in pregnant women. However, no effective treatment currently exists for hepatitis E, and the only cure is prevention. But so far there are no commercial vaccines for hepatitis E available in the world. Although at least four major genotypes of HEV have been identified to date, only one serotype of HEV is recognized. So there is a possibility to produce a broadly protective vaccine. Several studies for the development of an effective vaccine against hepatitis E are in progress and the best candidate at present for a hepatitis E vaccine is a recombinant HEV capsid antigen expressed in insect cells from a baculovirus vector. In this article, the recent advances of hepatitis E and the development of vaccine research for HEV including recombinant protein vaccine, DNA vaccine and the recombinant hepatitis E virus like particles (rHEV VLPs) are briefly reviewed.