Recombinant baculoviruses that express insect-specific toxins under the control of viral late gene promoters can kill susceptible lepidopteran hosts faster than the wild-type virus. In an effort to improve the efficacy of genetically engineered baculovirus pesticides, we have produced a recombinant that contains an insect specific toxin gene (AaIT) under the control of the promoter from an immediate early gene (ie1) of Autographa californica nuclear polyhedrosis virus (AcNPV). AaIT protein was detected as early as 4 h postinfection in cultured insect cells infected with this recombinant. The protein continued to accumulate as the infection progressed and, even as late as 24 h postinfection, the amount of AaIT was about equal to that provided by a recombinant that expressed AaIT under the control of the very late p10 promoter. Similar results were obtained with a recombinant that expressed a modified insect juvenile hormone esterase (JHE-KK) under ie1 control, confirming the ability of this promoter to provide early and abundant expression of gene products with potential pesticidal activity. Bioassays showed that the ie1-AaIT recombinant killed Heliothis virescens larvae faster than wild-type virus, but not faster than the p10-AaIT recombinant. However, larvae infected with the ie1-AaIT recombinant were smaller than those infected with the p10-AaIT recombinant, suggesting that expression of AaIT earlier in infection enhanced the ability of the virus to reduce the feeding activity of H. virescens larvae.
All Science Journal Classification (ASJC) codes
- Agronomy and Crop Science
- Insect Science