The Study Of Expression And Immunogenicity Of Rabbit Hemorrhagic Disease Virus Subgenome In The Insect Cell

Rabbit hemorrhagic disease (RHD) is a highly contagious and lethal infection that affects both wild and domestic rabbits. Its etiological agent, the rabbit hemorrhagic disease virus (RHDV), is considered to be the single most economically important disease of rabbits worldwide. The disease was first recognised in China but was subsequently isolated in other areas of Asia, different European countries, Mexico, and elsewhere. The etiological agent was identified as a calicivirus, a positive-sense, single-stranded RNA virus that is antigenically related to European brown hare syndrome virus. The complete genome of the virus has been elucidated for the German isolate and comprises a single-stranded positive-sense RNA genome of7,437nucleotides. The genome contains two open-reading frames, the first of which is2,344codons (ORF1) and encodes a large polyprotein containing the non-structural viral proteins and the viral coat protein, at the C-terminus.In the past20years, the capsid (VP60) gene has been successfully expressed in several heterologous systems and has been shown to induce the full protection of rabbits against lethal challenge with RHDV. However, none of these new types of vaccine against RHDV are available for field application. We believe that the main reasons are the low expression of VP60and the high cost of antigen purification from the host. Thus, the most important considerations for developing a new type of vaccine are improving the expression level of antigens and reducing the production cost. In this paper, the subgenome of RHDV was expressed in Sf9cells with bac-to-bac baculovirus expression systems; we hope that the expression level of VP60could be improved with the help of the non-coding region (NCR) and VP10of RHDV. The results of RT-PCR, indirect immnuofluorescence assay (IFA) and western blot analysis showed that RHDV VP60not only was successfully expressed well in Sf9cells, but also showed well immunogenicity. The results of Electron micrographs showed that VP60could self assemble virus-like particles (VLPs) in Sf9cells. The results of this study are helpful for further developing new type vaccines and virus packaging mechanism of RHDV.