Enhancing the insecticidal activity of recombinant baculovirus by expressing a growth-blocking peptide from the beet armyworm Spodoptera exigua

Insect cytokine growth-blocking peptides (GBPs) play functional roles in growth regulation and the innate immune response. Moreover, high concentrations of GBPs significantly induce larval morphological abnormalities and lethality. In the present study, a recombinant AcNPV, AcNPV-SeGBPm, expressing a growth-blocking peptide from the beet armyworm Spodoptera exigua (SeGBP) under the control of a polyhedrin promoter was constructed. Western blot analysis indicated that the mature peptide of SeGBP (SeGBPm) is expressed as a 3-kDa peptide in recombinant baculovirus-infected Sf9 insect cells. SeGBPm expression in Sf9 insect cells decreased cell viability significantly and induced apoptotic cell death. In addition, the body weights of S. exigua larvae inoculated with AcNPV-SeGBPm decreased significantly compared to those of larvae inoculated with wild-type AcNPV. Moreover, AcNPV-SeGBPm improved the rate of larvae killing (LT50) by approximately 1day compared to wild-type AcNPV. Taken together, the obtained data demonstrate the great potential for future investigations of growth-blocking peptides for use as biopesticides.