On the classification and nomenclature of baculoviruses: A proposal for revision

Recent evidence from genome sequence analyses demands a substantial revision of the taxonomy and classification of the family Baculoviridae. Comparisons of 29 baculovirus genomes indicated that baculovirus phylogeny followed the classification of the hosts more closely than morphological traits that have previously been used for classification of this virus family. On this basis, dipteran- and hymenopteran-specific nucleopolyhedroviruses (NPV) should be separated from lepidopteran-specific NPVs and accommodated into different genera. We propose a new classification and nomenclature for the genera within the baculovirus family. According to this proposal the updated classification should include four genera: Alphabaculovirus (lepidopteran-specific NPV), Betabaculovirus (lepidopteran-specific Granuloviruses), Gammabaculovirus (hymenopteran-specific NPV) and Deltabaculovirus (dipteran-specific NPV)

Recombinant, catalytically inactive juvenile hormone esterase enhances efficacy of baculovirus insecticides

The insecticidal efficacy of baculoviruses can be enhanced by engineering the viral genome to express proteins that disrupt the physiology of the host insect. Here we describe the development of a genetically engineered Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) which expresses a modified form of juvenile hormone esterase (JHE). Previously, two viruses expressing different modified JHEs were found to have a greater insecticidal effect on larvae of Trichoplusia ni and Heliothis virescens than a virus expressing wild-type JHE. To study a possible synergistic effect, the distinct mutations in the modified JHEs were combined in a new JHE construct. Two lysine residues were replaced with arginine residues to reduce the efficiency of lysosomal targeting (JHE-KK) and the catalytic serine was replaced with glycine, which eliminated catalytic activity (JHE-SG). The modified JHE, JHE-KSK, was expressed in a recombinant baculovirus, AcJHE-KSK. Larvae of H. virescens infected with this recombinant virus caused 44␕ess feeding damage to lettuce than larvae infected with the wild-type AcMNPV. However, AcJHE-KSK did not have significantly improved insecticidal properties over the parent viruses AcJHE-KK and AcJHE-SG, suggesting that the separate mutations have no major synergistic effect. Infection with a control recombinant baculovirus expressing JHE with the same lysine to arginine conversions and in which a catalytic histidine was converted to lysine (AcJHE-KHK) did not reduce feeding damage compared with that caused by larvae infected with AcMNPV