Cloning and characterization of two Campoletis chlorideae ichnovirus vankyrin genes expressed in parasitized host Helicoverpa armigera

Polydnaviruses, symbionts of parasitic ichneumonid (ichnoviruses, IVs) and braconid (bracoviruses, BVs), are injected into hosts along with wasp eggs. Within the host, PDV genes are expressed and their products function to alter lepidopteran host physiology and enable endoparasitoid development. In the present study, we describe two Campoletis chlorideae ichnovirus (CcIV) viral ankyrin (vankyrin) genes and their transcription. The CcIV vankyrin genes possess ankyrin repeat domains that resemble the inhibitory domains of the Drosophila melanogaster NF-κB transcription factor inhibitor (IκB) cactus. The expression of CcIV vankyrin genes could be detected in Helicoverpa armigera during the whole course of parasitization with two expression peaks, 30 min post-parasitization (p.p.) and 2 days p.p. Our data indicate that the CcIV vankyrin genes are differentially expressed in the tissues of parasitized hosts and both are mainly expressed in hemocytes. The temporal and spatial variation in expression of the two CcIV vankyrin genes suggests that CcIV vankyrin genes could be involved in early protection of parasitoid eggs from host cellular immune response by suppressing NF-κB signaling cascades, thereby altering development and immune responses of parasitized lepidopteran hosts.