An endoparasitoid wasp, Cotesia plutellae parasitized young larvae of diamondback moth, Plutella xylostella. Parasitized larvae exhibit sign ificant immunosuppression and fail to metamorphose to pupal stage. Especially, during last instar of parasitized P.xylostella, massive nutrients divert from host to wasp development. CpBV15α ,a host translation inhibitory factors encoded in C. Plutella bracovirus(CpBV), plays a crucial role in suppressing host usage of amino acids. Its promoter analysis shows that CpBV15α specifically inhibit host development in late larval period. To understand its inhibitory target, its specific expression was performed in non-parasitized P. xylostella by in vivo transient expression technique. Total plasma proteins were analyzed by 2D gel electrophoresis and determined target genes inhibited by CpBV15α. Immunoprecipation of cellular extract with CpBV15α antibody captured eIF2B. CpBV15α shares sequence homology with eIF5, especially at its eIF2B-binding region. Our results suggest that CpBV15α may sequester eIF2B, which result in malfunctioning of eIF2 cycling to form a translation initiation complex.