INSECTICIDAL ACTIVITY OF A RECOMBINANT BACULOVIRUS CONTAINING AN ANTISENSE C-MYC FRAGMENT

Attempts to develop baculovirus-based insecticides by insertion of gen es encoding enzyme inhibitors, neuropeptides or toxins have met with s ome success. However, it is often difficult to ensure correct processi ng or secretion of the encoded peptides. Here we tested a simpler stra tegy by insertion of an antisense fragment of a host gene to block tra nslation of a protein essential for larval growth and development. We selected the c-myc gene for two main reasons: (i) its protein is known to be well conserved in evolution and to have multiple essential func tions during development; and (ii) c-myc family genes have yet to be c haracterized in insects, thus blockage of essential genes by antisense transcripts from a strong virus promoter could provide a sensitive te st for the existence of myc-like gene products, An appropriate fragmen t of the human c-myc gene was inserted downstream from the polyhedrin promoter of Autographa californica nucleopolyhedrovirus and tested in bioassays on Spodoptera frugiperda larvae. Western blot analysis with a human c-myc antibody revealed an endogenous protein band which bound specifically to these antibodies. This band disappeared more rapidly from cells infected with the antisense c-myc recombinant virus than fr om those infected with c-myc-negative virus. Results of bioassays show ed that the antisense construct stopped feeding as soon as the polyhed rin promoter-driven transcripts accumulated, followed shortly by death of the larvae. These results suggest that c-myc-like protein(s) exist in insects and that the antisense strategy is an effective approach t o virus insecticide production.