The parasitoid wasp Campoletis sonorensis possesses an obligate symbiotic Ichnovirus (CsIV) that is required by the wasp for successful parasitization of larval lepidopteran hosts. During parasitization, CsIV virions are injected with an egg and ovarian proteins into a permissive host of the wasp where viral gene products function to alter host physiology and enable the survival of wasp progeny. Analysis of the CsIV genome identified the presence of a novel gene family in the virus represented by seven 500-bp open reading frames possessing ankyrin repeat protein motifs. The viral ankyrin motifs in CsIV carry similarity to the ankyrin repeat domains of the Drosophila dorsal/NF-kb transcription factor inhibitor cactus, a member of the Ikb gene family. We hypothesize that viral ankyrin (vankyrin) proteins from CsIV may be functioning in a similar manner to Ikb proteins to suppress NF-kb-mediated signaling disrupting immunity and development in parasitized larvae. At least 5 of the 7 genes are expressed in Heliothis virescens hosts within 4 hours of parasitization. Antibodies raised against one of the viral genes react strongly with a protein of the appropriate size in extracts of 1-4 day parasitized H. virescens fat body tissue and with recombinant vankyrin protein expressed from a baculovirus. Immunofluorescence data suggest that vankyrin proteins localize to the parasitized fat body nucleus. Recombinant vankyrin proteins are currently being expressed in a baculovirus and will be purified for future analyses such as electrophoretic mobility shift and immunofluorescence assays to provide further insights into gene function and cellular localization patterns.
Species 1: Hymenoptera Ichneumonidae Campoletis sonorensis
Species 2: Lepidoptera Noctuidae Heliothis virescens (tobacco budworm)
Keywords: ichnovirus, ankyrin
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