Construction of an improved baculovirus insecticide containing an insect-specific toxin gene

Abstract

Baculoviruses provide alternatives to chemicals for controlling insect pests and can be applied by spraying. Baculoviruses have a limited host range, but work relatively slowly. They are dissolved in the midgut of insect larvae to release infectious virions which enter gut epithelial cells and begin to replicate. Replication in other organs causes extensive tissue damage and eventually death. This process can take 4-5 days, but in the field may last for more than a week, allowing the larvae to feed for longer and thereby damaging the host plant. Baculovirus expression vectors expressing foreign genes, such as those for insect-specific toxins, hormones or enzymes, might alleviate this problem. We have now constructed a recombinant baculovirus derived from Autographa californica nuclear polyhedrosis virus containing an insect-specific neurotoxin from the venom of the North African (Algerian) scorpion, Androctonus australis Hector. The neurotoxin acts by causing specific modifications to the Na+ conductance of neurons, producing a presynaptic excitatory effect leading to paralysis and death; it has no effect in mice. Expression of the neurotoxin by the virus causes a reduction in the time required to kill the host insect.

Functional expression of an alpha anti‐insect scorpion neurotoxin in insect cells and lepidopterous larvae

“…2,3,4 and Tables 1 and 2). Previous studies reported that baculovirus-directed functional expression of the excitatory anti-insect selective scorpion toxin AaIT fused to a signal peptide coding sequences of an insect protein bombyxin or of the baculovirus protein gp67 [12][13][14]. In the present study, we demonstrate that expression, secretion and correct processing of LqhcdT can be achieved by direct cloning of its cDNA, including the LqhczIT signal peptide coding sequences.…”

Poneratoxin, a neurotoxin from ant venom

“…This is shortened with the parental baculovirus infection to about 7 days and to 5-6 days with recombinant SPx baculovirus. Similar results have been obtained with recombinant baculoviruses expressing neurotoxins of the scorpion A. australis or the mite Pyemotes tritici 5 [6,7,49]. We think that further improvements could be obtained by adjusting the secretion pathway to imitate the native one.…”

“…The two helices have quite different characters. The first, PLLILGS (3)(4)(5)(6)(7)(8)(9), is apolar, whereas the second, IQ-AIHDAQR (17)(18)(19)(20)(21)(22)(23)(24)(25), contains polar and charged amino acids. This will result in different interactions with cell membranes.…”

“…It seems likely that when not exported, this peptide is either destroyed inside the cell or is toxic for the cells. Sequence analysis suggested that the part LPLLILGSLLMTPPVIQA (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19), which looks like a transmembrane segment is similar to signal peptides of a variety of proteins [34]. If without an authentic signal peptide this fragment is seen by the expressing cell as a signal peptide, it could be degraded by the appropriate enzymatic system such as one that cleaves the signal peptide of preprolactine within its hydrophobic core, between two leucine clusters [35].…”

Induction of antitumor immunity against mouse carcinoma by baculovirus-infected dendritic cells

“…2 Baculoviruses have long been used as biopesticides 3,4 and recombinant protein expression systems. 5,6 Recent research has focused on the use of baculoviruses as vectors in gene therapy because of (1) their ability to infect, but not replicate in, mammalian cells; (2) their low cytotoxicity; and (3) their ability to carry large foreign genes into their genome.…”