MacoNPV baculovirus midgut-specific gene expression during infection of the bertha armyworm, Mamestra configurata

Baculoviruses are ubiquitous DNA viruses of insects, including many pests of agriculture, and these viruses are thus of interest as potential pest control tools. Baculoviruses exist in two forms, one which is responsible for primary infection in the host gut, and a second, which infects all other host tissues during secondary infection. This study examined primary infection of midgut cells in larvae of the bertha armyworm, Mamestra configurata, and measured the expression of viral genes over a time course of infection. Two methods of measurement showed viral gene transcription in the insect gut to be different from that produced by infection of cultured insect cells produced by a closely related virus. The differences included having unique collections of genes expressed early, as well as very different levels of genes expressed late, including p6.9 (much higher), and polh and p10 (much lower). These differences indicate there are characteristics unique to the critical steps of virus infection within the insect gut as distinct from cells in tissue culture. The results help us understand the processes that regulate viral gene expression in different host tissues, which is crucial for enabling these viruses to be used effectively as biopesticides.