Submitted to: Biopesticides International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/5/2007
Publication Date: 10/7/2007
Citation: Raina, A.K., Vakharia, V.N., Leclerc, R.F., Blackburn, M.B. 2007. Engineering a Recombinant Baculovirus with a Peptide Hormone Gene and its Effect on the Corn Earworm, Helicoverpa zea. Biopesticides International. 3(1):43-52. Interpretive Summary: Baculoviruses are insect specific viruses that could be very important in pest management except that their action is generally slow resulting in continued feeding on the host. Incorporation of foreign genes, like the spider and scorpion toxins have been suggested and tried. Regulation of water balance in insects is controlled by peptide hormones that are safe and fairly specific. We cloned one and two copies of the gene for diuretic hormone of the corn earworm into a baculovirus. When newly hatched larvae of the corn earworm were fed on the engineered baculovirus not only did it cause higher and faster mortality, the infected larvae did not feed at all. With further improvements in the cloning process, this could be a very effective tool in the management of crop pests.
Technical Abstract: The helicokinins are peptides identified from Helicoverpa zea that when injected into the larvae were found to cause excessive diuresis and loss of feeding activity. Of the three peptides, helicokinin II (HezK-II) was found to be most potent. A synthetic gene encoding HezK-II was constructed based on the codon usage of 44 proteins of lepidopteran origin. A gene cassette containing the synthetic gene, HezK-II, downstream of a human placental alkaline phosphatase signal sequence was inserted into the baculovirus Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV). Two constructs were generated, one (AcHezK-II S) contained a single copy of the HezK-II gene under a polh promoter and the other (AcHezK-II M) contained two copies of HezK-II under polh and p10 promoters. Exposure of neonate H. zea to artificial diet that was surface contaminated with recombinant AcHezK-II S or AcHezK-II M indicated that AcHezK-II M exposure resulted in significantly lower weight gain, mortality, and pupation rates in comparison to larvae infected with wild type (WT) AcMNPV at 7 and 14 days post exposure. Larvae exposed to AcHezK-II S showed significantly lower weight gain, mortality, and pupation rates in comparison to WT AcMNPV at 14 days post virus exposure, but not at 7 days post exposure.