Utility of polydnavirus genes in biotechnology applications

Polydnaviruses markedly alter the physiology of their insect hosts, most notable through suppression of immune responses to parasitoid eggs and arrest of the development of their larval lepidopteran hosts. Genes responsible for these physiological effects have been described in several polydnavirus systems including that of the Campoletis sonorensis ichnovirus (CsIV). Notably, CsIV genes, the viral ankyrin or vankyrin genes, are related to inhibitors of NF-κβ signaling and inhibit immune responses to virus infection such as apoptosis. The ability of CsIV vankyrin genes to inhibit virus-induced apoptosis may have utility in biotechnology. In particular, CsIV genes have been used to transform insect cells used for protein expression in the baculovirus-expression vector system (BEVS). The transformed cells exhibit delayed lysis and markedly enhanced recombinant protein synthesis when infected with recombinant baculoviruses.This increase in protein production is a valuable phenotype that has been commercialized. A similar increase in recombinant protein expression is observed when CsIV vankyrin genes are expressed from the recombinant virus itself in a ‘dual-expression’ system. Interestingly, recombinant proteins that are secreted and glycosylated appear to be expressed at higher levels, perhaps because the inhibition of the apoptotic pathway allows protein processing pathways to remain intact for a longer time post viral infection. Taken together, these data and our experience with the CsIV vankyrin genes indicate that polydnavirus genomes encode genes having potential utility in diverse biotechnological applications.