A baculovirus gene inducing hyperactive behavior in caterpillars

Many parasites manipulate host behavior to increase the probability of transmission. To date, however, knowledge on parasitic genes underlying such behavioral manipulations is scarce. Here we show that the baculovirus Autographa californica nuclear polyhedrovirus (AcMNPV) induces hyperactive behavior in Spodoptera exigua caterpillars at three days after infection. Furthermore, we identify the viral protein tyrosine phosphatase (ptp) gene as a key player in the induction of hyperactivity in larvae, and show that the phosphatase activity of the encoded enzyme is crucial for this behavioral change. Phylogenetic inference points at a lepidopteran origin of the viral ptp gene. Our study suggests that ptp-induced behavioral manipulation is an evolutionary conserved strategy of baculoviruses to enhance virus transmission. In addition, we show that larvae move downward after AcMNPV infection, which appears to be a ptp-independent process. Overall, these data provide a firm base for a deeper understanding of the mechanisms behind baculovirus-induced insect behavior.