Baculovirus Controls Host Catapillars by Manipulating Host Physiology and Behavior

Abstract

Nucleopolyhedroviruses (NPVs) belonging to the family Baculoviridae are large, envel- oped, double-stranded DNA viruses that are pathogenic to insects. The Bombyx mori NPV (BmNPV) is an NPV pathogenic to the domesticated silkworm B. mori. DNA sequencing revealed that BmNPV potentially encodes 136 putative proteins. Mutagenesis experi- ments have discovered the viral proteins that control host catapillars at cellular and/or organismal levels: ecdysteroid UDP-glucosyltransferase inactivates an insect molting hormone ecdysone, protein tyrosine phosphatase is involved in wandering behavior at the late stage of infection, fibroblast growth factor induces host cell chemotaxis, and chitinase and cathepsin are required for postmortem host liquefaction. Furthermore, com- parative analyses of the genomes of B. mori and baculoviruses have revealed that the modern lepidopteran baculoviruses may have acquired and modified several genes from an ancestral host insect to control the physiology of their own hosts and to increase the efficiency of virus transmission in nature. In this review, I describe our research progress on functional analyses of BmNPV genes that are involved in manipulating host physiol- ogy and behavior.