Translational Control of Host Gene Expression by a Cys-Motif Protein Encoded in a Bracovirus.
Translational control is a strategy that various viruses use to manipulate their hosts to suppress acute antiviral response. Polydnaviruses, a group of insect double-stranded DNA viruses symbiotic to some endoparasitoid wasps, are divided into two genera: ichnovirus (IV) and bracovirus (BV). In IV, some Cys-motif genes are known as host translation-inhibitory factors (HTIF). The genome of endoparasitoid wasp Cotesia plutellae contains a Cys-motif gene (Cp-TSP13) homologous to an HTIF known as teratocyte-secretory protein 14 (TSP14) of Microplitis croceipes. Cp-TSP13 consists of 129 amino acid residues with a predicted molecular weight of 13.987 kDa and pI value of 7.928. Genomic DNA region encoding its open reading frame has three introns. Cp-TSP13 possesses six conserved cysteine residues as other Cys-motif genes functioning as HTIF. Cp-TSP13 was expressed in Plutella xylostella larvae parasitized by C. plutellae. C. plutellae bracovirus (CpBV) was purified and injected into non-parasitized P. xylostella that expressed Cp-TSP13. Cp-TSP13 was cloned into a eukaryotic expression vector and used to infect Sf9 cells to transiently express Cp-TSP13. The synthesized Cp-TSP13 protein was detected in culture broth. An overlaying experiment showed that the purified Cp-TSP13 entered hemocytes. It was localized in the cytosol. Recombinant Cp-TSP13 significantly inhibited protein synthesis of secretory proteins when it was added to in vitro cultured fat body. In addition, the recombinant Cp-TSP13 directly inhibited the translation of fat body mRNAs in in vitro translation assay using rabbit reticulocyte lysate. Moreover, the recombinant Cp-TSP13 significantly suppressed cellular immune responses by inhibiting hemocyte-spreading behavior. It also exhibited significant insecticidal activities by both injection and feeding routes. These results indicate that Cp-TSP13 is a viral HTIF.
Department of Bioresource Sciences, Andong National University, Andong 36729, Republic of Korea.
Eunseong
E
Kim
Department of Bioresource Sciences, Andong National University, Andong 36729, Republic of Korea.
Yonggyun
Y
Kim
D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D004247:DNA / Q000235:genetics; D006790:Host-Parasite Interactions / Q000235:genetics*; D007304:Insect Viruses / Q000235:genetics* / Q000472:pathogenicity; D016366:Open Reading Frames; D018071:Polydnaviridae / Q000235:genetics* / Q000472:pathogenicity; D014764:Viral Proteins / Q000235:genetics; D014863:Wasps / Q000235:genetics / Q000821:virology*
D014764:Viral Proteins; D004247:DNA