Development of a recombinant baculovirus expressing a modified juvenile hormone esterase with potential for insect control

Abstract

and Environmental Microbiology, Oafo~d, UK (TEB.)Baculovirus insecticides are receiving renewed attention as insect pest control agents following the development of fast-acting recombinant baculoviruses. Here we report on the construction and biological activity of a recombinant baculovirus derived from the nuclear polyhedrosis virus of Autograph californica which expresses a modified form of juvenile hormone esterase (JHE). The serine at the catalytic site of the JHE has been mutated to a glycine residue so that the protein does not degrade JH. The recombinant baculovirus expressing this modified form of JHE, named AcJHE-SG, has enhanced activity against lepidopteran larvae. Lethal times of the recombinant are 20 to 30% lower than for the wild type virus, and a 66% reduction in feeding damage caused by infected larvae is observed. This result is comparable to the best recombinant baculovirus developed to date, AcAalT, which expresses an insect-selective scorpion toxin. The potential of these recombinant viruses for commercialization as insecticides is discussed. Bioassays of AcJHE-SG in conjunction with anti-JH agents indicate that the virus is not killing by an anti-JH mechanism. Larvae apparently die from contraction-paralysis, or disruption of the normal sequence of events at the molt. o 1995 Wiley-Liss, Inc.

A Chrysodeixis chalcites Single-Nucleocapsid Nucleopolyhedrovirus Population from the Canary Islands Is Genotypically Structured To Maximize Survival

“…Improvement of the speed of kill has been one of the major research objectives in the development of recombinant baculoviruses as the basis for bioinsecticidal products. Two main approaches have been employed-the expression of insecticidal toxins, enzymes, or hormones (47,48,49) or the deletion of genes affecting the life stage (50)-or a combination of both (51). In the present study, we demonstrated that coocclusion of certain genotypes within the same OB resulted in a significant improvement in the speed of kill.…”

Expression of a Non-Secreted Form of Juvenile Hormone Esterase in a Baculovirus

“…These effects were probably due to the abnormal accumulation of NSJHE in cells, but not due to overexpressed JHE activity. As several attempts to express modified JHE in baculovirus systems have proved successful in improving virus insecticidal activities: for example, SG-JHE, which was modified at catalytic sites 2 , and KK-JHE, which was mutated at putative lysosomal targeting sites 3 , further modification of the JHE gene by addition of ER retention-or membrane anchor-signals so as to synthesize JHE via the ER lumen may improve expression efficacy of NSJHE.…”

Abnormal development in larvae of Sesamia nonagrioides (Lepidoptera: Noctuidae) resulting from baculovirus-mediated overexpression of a JHE-related gene (SnJHER)

“…JHE-KK in which two lysine residues were replaced with arginine residues to reduce the effi ciency of lysosomal targeting; JHE-SG in which the catalytic serine was replaced with glycine, which eliminated catalytic activity; JHE-KSK, which contained a combination of the above mutations; and JHE-KHK which is also based on JHE-KK but in which a catalytic histidine was converted to lysine (Bonning et al, 1995(Bonning et al, , 1997(Bonning et al, , 1999van Meer et al, 2000). These experiments showed that JHE-KK is resistant to degradation in pericardial cells (Bonning et al, 1997), which resulted in 15% of the larvae showing symptoms of contraction paralysis (Bonning et al, 1999).…”

“…These experiments showed that JHE-KK is resistant to degradation in pericardial cells (Bonning et al, 1997), which resulted in 15% of the larvae showing symptoms of contraction paralysis (Bonning et al, 1999). In contrast, JHE-SG disrupted the moulting process; a considerable proportion of the larvae infected with AcJHE-SG died at the moult after developing extreme cuticular blackening (Bonning et al, 1995). Consequently biochemical analysis of JHE-KHK and JHE-KSK produced in insect cell cultures showed that mutation of the catalytic site serine in JHE-KSK or histidine in JHE-KHK removes all JHE catalytic activity (van Meer et al, 2000).…”