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356-365
- Zusammenfsg.
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The parasitoid wasp Cotesia kariyai (C.k.) parasitizes the larvae of the armyworm Mythimna(Pseudaletia)separata. The C.k. wasps carry polydnaviruses that induce a variety of physiological changes in immunity and development of the host armyworm larvae, which contribute to the survival of the wasp eggs and larvae. We have analyzed the process of C.k. polydnavirus (CkPDV) replication in the reproductive tracts of the female wasps. A previous study showed that one of CkPDV surface proteins mediates immunoevasion by the wasp from the encapsulation reaction of the host insect's hemocytes, thereby it was named immu-noevasive proteins (IEP). We isolated the IEP cDNA, sequenced it, and found that this is a cystein-rich protein containing epidermal growth factor (EGF)-like repeats. IEP gene is not present in the CkPDV genome, but in the wasp chromosomal DNA. The IEP mRNA and protein are expressed in the lateral oviducts, while capsid proteins are expressed in calyx cells of the female reproductive tracts. In the couse of the viral replication, the capsid proteins were detected from 3 days after pupation, being followed by the IEP synthesis one day later. These results suggest that the expression pattern and localization of IEP and capsid proteins are clearly different. Therefore, it is reasonable to assume that the complete CkPDV virion is not composed simultaneously in the calyx cells but requires gradual steps both in the calyx cells and lateral oviducts.
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