Improved insecticidal efficacy of a recombinant baculovirus expressing mutated JH esterase from Manduca sexta

Juvenile hormone esterase (JHE), amember of the carboxylesterase family (EC 3.1.1.1), metabolizes JH that is found in juvenile insects. A highly conserved amphipathic alpha helix is found on the surface of known JHEs. This helix is implicated in receptor-mediated binding and endocytosis of JHE by the pericardial cells resulting in the clearance of JHE activity from the hemolymph. In this study, Lys-204 and Arg-208 of the amphipathic alphahelix of the JHEofManduca sexta (MsJHE)weremutated to histidine residues generating MsJHE-HH. Pharmacokinetic studies following the injection of MsJHE-HH into the hemocoel of larval M. sexta, Heliothis virescens, and Agrotis ipsilon indicated that MsJHE-HH and wild type MsJHE are cleared at similar rates. The infectivity (lethal concentration and lethal time) of a recombinant baculovirus, AcMsJHE-HH, expressingMsJHE-HHwas not significantly different than that of a recombinant baculovirus, AcMsJHE, expressingMsJHE in first instars ofH. virescens and A. ipsilon. However, themass of AcMsJHE-HHinfected larvaewas 40–50% lower than that of larvae infectedwith AcMsJHE, and 70–90% lower than that of wild type AcMNPV-infected larvae. 2011 Elsevier Inc. All rights reserved.