Properties of Three Baculovirus-Expressing Genes That Encode Insect-Selective Toxins: μ-Aga-IV, As II, and Sh I

We have chemically synthesized and expressed three chimeric genes,mag4, sat2,andssh1,that encode secretable polypeptides with neurotoxic activity in insects.mag4encodes the μ-Aga-IV toxin from the spiderAgelenopsis apertaand has a mellitin signal sequence from the honey beeApis mellifera.The other two genes,sat2andssh1,encode As II and Sh I toxins from the sea anemonesAnemonia sulcataandStichodactyla helianthus,respectively, and have a sarcotoxin signal sequence from the flesh flySarcophaga peregrina.The synthetic genes were inserted into a nonessential site in the genome of theAutographa californicanuclear polyhedrosis virus under the control of an enhanced polyhedrin promoter. In all cases, insect cells infected with recombinant viruses produced toxins, and larvae infected with the recombinant viruses died more quickly than larvae infected with wild-type virus. The relative efficacy of themag4-expressing recombinant was host-dependent. InTrichoplusia ni, sat2expression was most effective, providing a 38.4% reduction in time to death compared to the wild-type virus, while inSpodoptera frugiperda,themag4-expressing recombinant was most effective, exhibiting a 37% reduction in time to death.