3H-117 encoded by Heliothis virescens ascovirus 3h interferes the oral activity of AcMNPV

Abstract:

[Objective] Ascoviruses are humor transmitted insect viruses that have unique pathogenicity and are competent to develop into bioinsecticides. Heliothis virescens ascovirus 3h (HvAV-3h) is the first ascovirus strain that isolated in China, and the 3H-117 protein encoded by HvAV-3h are reported as a structural protein of HvAV-3h.[Methods] In order to further illustrate the function of 3h-117, the Bac-to-Bac insect expression system was employed to construct a recombinant Autographa californica multiple nuclepolyhedrovirus (AcMNPV) by inserting 3h-117 into the genome of AcMNPV.[Results] Compared with the wild type control AcMNPV (AcMNPV-Egfp), the generated recombinant baculoviurs (AcMNPV-117) had a significantly reduced budded virus production and viral DNA copies in the infected Sf9 cells during 72-96 hpi, and an enlarged occlusion bodies was found in AcMNPV-117. Further bioassays showed that the 90% lethal dosage of AcMNPV-117 against the third instar Spodoptera exigua are significantly higher than the 90% lethal dosage of AcMNPV-Egfp. Furthermore, the growth of the tested S. eixuga larvae infected with AcMNPVs was slower than that of the healthy larval growth, and the average daily food intake of the tested larvae was also inhibited by the baculovirus infection. The confocal observation showed that 3H-117 is associated with the nuclear actin polymerization in AcMNPV-117 infected Sf9 cells, which indicated that the function of 3H-117 in the infectious procedures of ascovirus is associated to the disintegration of host cell nucleus.[Conclusion] The results obtained in this study confirmed the function of 3h-117, which laid a foundation for the molecular biology research of ascovirus.

Key words:Heliothis virescens ascovirus 3h (HvAV-3h);recombinant baculovirus;Autographa californica multiple nuclepolyhedrovirus (AcMNPV);Bac-to-Bac insect expression system;biological assays