Genomic sequence and biological characterization of a nucleopolyhedrovirus isolated from the summer fruit tortrix, Adoxophyes orana

Abstract

Adoxophyes orana nucleopolyhedrovirus (AdorNPV) was isolated from overwintering larvae from an orchard in the UK. The nucleotide sequence of the AdorNPV DNA genome was determined and analysed. The genome contains 111724 bp and has a G+C content of 35.0 mol%. The analysis predicted 121 ORFs of 150 nt or larger. Of these putative genes, 118 were homologous to genes identified previously in the Adoxophyes honmai nucleopolyhedrovirus (AdhoNPV) genome (83.3-100 % aa identity), and three AdorNPV ORFs were unique. There were four small homologous regions that consisted of a similar core sequence and at the same relative positions in the genome as AdhoNPV, but they differed in the number of repeats and orientation. Some genes that have been reported to have major roles in baculovirus biology were either absent or truncated in the AdorNPV genome. These included chitinase, which is involved in the liquefaction of the host, and the C-terminal of the ecdysteroid UDP-glucosyltransferase (egt) protein, which was truncated by 149 aa compared with AdhoNPV, with essential amino acids absent. The AdorNPV genome encoded two inhibitor of apoptosis (iap) genes compared with three in AdhoNPV and three bro genes compared with four in AdhoNPV. The susceptibility of A. orana larvae to AdorNPV was evaluated in laboratory bioassays using inoculation by microdroplet feeding and applied dose assays. LD 50 for neonates was 56 occlusion bodies rising to 2.3¾10 4 for fifth instar larvae. Median survival time values using an LD 80 dose were 8.8 days for neonates and 7.0 days for fifth instar larvae. INTRODUCTIONThe family Baculoviridae consists of invertebrate viruses with large circular, covalently closed, double-stranded DNA genomes with enveloped nucleocapsids and an occluded form of the virus embedded in proteinaceous occlusion bodies (OBs) . There are two genera of baculovirus, the Nucleopolyhedrovirus (NPV) and the Granulovirus (GV) based on OB morphology . The NPVs are further classed into group I and II NPVs (Bulach et al., 1999;Zanotto et al., 1993). The majority of the sequenced NPVs infect insects of the Lepidopteran order, but NPVs that infect dipteran or hymenopteran insect species like the mosquito-infecting Culex nigripalpus NPV, or the NPVs from three Neodiprion species, have been sequenced (Afonso et al., 2001;Garcia-Maruniak et al., 2004;Lauzon et al., 2004; Duffy et al., 2006). Baculoviruses are used worldwide as biological control agents of agricultural and forest pests. The summer fruit tortrix moth (Adoxophyes orana) is a pest of apples and pears in most of Europe and Japan.During the past 25 years, there has been increased interest in the use of a naturally occurring GV as a control agent for the summer fruit tortrix (Cross et al., 1999). Recently, a mixture of baculoviruses was recovered from larvae in the UK (Hilton & Winstanley, 2008). These were separated and found to comprise an NPV and a GV. The GV (Adoxophyes orana GV) has been characterized and completely sequenced (Wormleaton et al., 2003;Hilton & Winstanley, 2...

Isolation of an Adoxophyes orana granulovirus (AdorGV) occlusion body morphology mutant: biological activity, genome sequence and relationship to other isolates of AdorGV

“…These species are closely related (Sakamaki & Hayakawa, 2004;Yasuda, 1998). Similarly, GVs isolated from A. orana and A. honmai yielded identical restriction fragment patterns by restriction endonuclease analysis, suggesting they are variants of the same species (Hilton & Winstanley, 2008).…”

“…GV genes that influence susceptibility to inactivation by UV light may therefore be under positive selection pressure (Yang, 2001). To identify genes in AdorGV-M that may have undergone positive selection during the divergence of the AdorGV-M and AdorGV-E isolates, the non-synonymous and synonymous (Hilton & Winstanley, 2008;Nakai et al, 2003), as well as a less conserved homologue in the Agrotis segetum granulovirus sequence (GenBank accession no. YP_006286).…”

Morphology and genome of Euproctis pseudoconspersa nucleopolyhedrovirus

“…Lef4, lef8, lef9, p47, vlf1, lef5 which were present in all baculovirus and 39 K, lef6, lef11 which were present in all lepidopteran baculovirus were all present in EupsNPV genome. At the immediately early stage of baculovirus replication, host cell RNA polymerase II should be activated by genes such as i.e-0, i.e-1, i.e-2 and pe38 [23]. EupsNPV contained i.e-0 and i.e-1, but not i.e-2 and pe38 which were unique to group I NPVs.…”

Juvenile hormone (JH) esterase activity but not JH epoxide hydrolase activity is downregulated in larval Adoxophyes honmai following nucleopolyhedroviruses infection

“…Isolates of NPVs of A. honmai (AdhoNPV) (Ishii et al, 2003;Nakai et al, 2003) and A. orana (AdorNPV) (Hilton and Winstanley, 2008b) were used in this study. Larval A. honmai are permissive to both AdhoNPV and AdorNPV (Takahashi et al, 2008).…”