38th Annual Meeting of the Society for Invertebrate Pathology

A full length cDNA clone of the Rhopalosiphum padi virus (RhPV) genome was inserted into the genome of Autographa californica nucleopolyhedrovirus to create the recombinant baculovirus AcRhPV6. Expression of the RhPV genome in Sf21 cells resulted in formation of RhPV virus-like particles (VLPs) whose capsids are structurally and immunologically indistinguishable from the native virions. The presence of genomic RhPV RNA in recombinant baculovirus infected cells and in VLPs was confirmed by RT-PCR. Assembly of RhPV VLPs in the nucleus of baculovirus infected cells suggests that in Sf21 cells (i) both the 5’ and IGR IRES of RhPV are active, (ii) the virus encoded protease is functional for processing of RhPV polyproteins, and (iii) replication of RhPV is not required for encapsidation of RNA. For analysis of the infectivity of baculovirus expressed RhPV6, virions purified from baculovirus-infected Sf21 cells were fed to the bird cherry-oat aphid, Rhopalosiphum padi. Aphids were tested for infection by the baculovirus-produced RhPV clone by RT-PCR and western blot analysis, four weeks after acquisition. Baculovirus expression of RhPV in lepidopteran cell lines that do not support replication of RhPV provides a potential alternative approach for in vitro production of clones of this virus.