Crude extracts of recombinant baculovirus expressing rabbithemorrhagic disease virus 2 VLPs from both insect and rabbit cellsprotect rabbits from rabbit hemorrhagic disease caused by RHDV2

AbstractVaccines against viral pathogens are often composed of recombinant proteins expressed in different systems. Such proteinsexpressed by recombinant baculoviruses have been proven to be effective for vaccination. Especially, after codon usageoptimization high amounts of recombinant viral proteins can be obtained which can assemble to virus like particles (VLPs)spontaneously. In this study we compared two different codon usages of RHDV2-VP1 to improve the expression of recombinantVP1 of RHDV2 by recombinant baculoviruses after infection of insect SF9 cells or transduction of mammalian RK13cells in order to gain high protein yields. Also the influence on the auto-assembly of RHDV2-VP1 to VLPs was investigated.Finally, the immunogenic potential of such recombinant vaccines against RHDV2 to induce a protective immune responsein rabbits against RHDV2 should be characterized. There was no influence of different codon usages on RHDV2-VP1 geneexpression in the respective cell lines detected. However, in insect cell line SF9 higher rates of recombinant VP1 were measuredin comparison to the transduction of mammalian cells RK13. Auto-assembly of RHDV2-VP1 to VLPs was observedin both cell systems by electron microscopy. Finally, both RHDV-VP1 VLPs derived from mammalian and insect cells wereable to induce a protective humoral immune response in rabbits against RHDV2