Development of a vectored vaccine against hepatitis E virus

Abstract

Hepatitis E virus is a non-enveloped ssRNA virus [1] that causes human acute hepatitis through primarily fecal and oral transmission [2]. Currently, no commercial hepatitis E (HEV) vaccine is available. In the absence of an appropriate cell culture system for HEV propagation, HEV pseudocapsids (ORF2 protein) have been produced either in Escherichia coli or in insect cells and they have been shown to protect monkeys against virus challenge and to be effective in the prevention of natural HEV infection of humans. In this work, we propose to develop a novel candidate vaccine against hepatitis E infection using adeno-associated virus (AAV) as a vector expressing the gene of the truncated capsid protein of HEV (aa 112-aa 660). rAAV will be produced in Sf9 cells using the baculovirus expression vector system. For this purpose, construction of recombinant baculoviruses was performed and viral stocks of BacRep, BacCap for serotypes 2, 5 and 6 were prepared in Sf9 cells. The recombinant baculovirus coding for the truncated capsid protein of HEV (BacITRHEVORF2) was also constructed, the virus titer was equal to 5.41×10(9) PFU/mL, at the third passage. Transduction of HEK 293 EBNA cells with rAAV was carried out; the production of HEVORF2 was confirmed by Western blot. Optimization of rAAV production in Sf9 cells is currently ongoing.

Keywords: Adeno-associated virus; Baculovirus; Hepatitis E virus; Insect cells SF9.