Interaction of a wasp ovarian protein and polydnavirus in host immune suppression

During parasitization of Heliothis virescens, Campoletis sonorensis deposits an egg along with venom, poly-DNA-virus particles (CsPDV), and ovarian proteins (OPs). Oviposited eggs are not encapsulated, while washed eggs are encapsulated rapidly by H. virescens. Early protection from encapsulation is afforded by a group of 29-36 kD OP glycoforms. These glycoforms are endocytosed by host hemocytes within 30 min post-parasitization (pp) and disrupt hemocyte spreading behavior and egg encapsulation through at least 24 h pi. Purified CsPDV does not protect eggs from encapsulation early, but disrupts hemocyte spreading and egg encapsulation from 24 h through at least 5 days pi. Functional activity of CsPDV appears to be correlated with time-dependent accumulation of virus-specific proteins in parasitized insects. We propose that the fast-acting 29-36 kD OP protects Campoletis eggs from encapsulation until accumulation of CsPDV proteins which sustain immunosuppression.