Changes in gene expression in the permissive larval host lightbrown apple moth (Epiphyas postvittana, Tortricidae) in response to EppoNPV (Baculoviridae) infection

Abstract

Host cell and virus gene expression were measured five days after per os inoculation of 3rd instar lightbrown apple moth (LBAM) larvae with the Epiphyas postvittana nucleopolyhedrovirus (EppoNPV). Microarray analysis identified 84 insect genes that were up-regulated and 18 genes that were down-regulated in virus-infected larvae compared with uninfected larvae. From the 134 viral open reading frames represented on the microarray, 81 genes showed strong expression. Of the 38 functionally identifiable regulated insect genes, 23 coded for proteins that have roles in one of five processes; regulation of transcription and translation, induction of apoptosis, and maintenance of both juvenility and actin cytoskeletal integrity. Of the 34 functionally identifiable viral genes that were most strongly expressed, 12 had functions associated with these five processes, as did a further seven viral genes which were expressed at slightly lower levels. A survey of the LBAM-expressed sequence tag library identified further genes involved in these processes. In total, 135 insect genes and 38 viral genes were analysed by quantitative polymerase chain reaction. Twenty-one insect genes were strongly up-regulated and 31 genes strongly down-regulated. All 38 viral genes examined were highly expressed. These data suggest that induction of apoptosis and regulation of juvenility are the major 'battlegrounds' between virus and insect, with the majority of changes observed representing viral control of insect gene expression. Transcription and translational effects seem to be exerted largely through modulation of mRNA and protein degradation. Examples of attempts by the insect to repel the infection via changes in gene expression within these same processes were, however, also noted. The data also showed the extent to which viral transcription dominated in the infected insects at five days post inoculation.

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

“…5). These findings are consistent with another study using Epiphyas postvittana (Lepidoptera: Tortricidae) infected with E. postvittana NPV (EppoNPV) that also showed roughly 4-fold downregulation of the expression of a putative jhe gene (Gatehouse et al, 2009). Interestingly, this previous study also showed downregulation of four putative JHEH-encoding genes.…”

“…Total RNA from whole body was extracted every 24 h after inoculation as described in Section 2.5. b-actin of A. honmai was selected as a reference gene for qRT-PCR as suggested previously (Anand et al, 2008;Gatehouse et al, 2009). Primers were designed from ahjhe and partial sequence of b-actin of A. honmai.…”

Entomopoxvirus infection induces changes in both juvenile hormone and ecdysteroid levels in larval Mythimna separata

“…For example, in baculovirus-infected larval Epiphyas postvittana infected with Epiphyas postvittana nucleopolyhedrovirus (Gatehouse et al, 2009) and larval Adoxophyes honmai , JH levels are maintained by the suppression of jhe gene expression, which in turn results in reduced JHE activity. Additional studies, however, are needed to establish whether MySEV is able to alter gene expression levels in M. separata.…”

Digital gene expression analysis of Helicoverpa armigera in the early stage of infection with Helicoverpa armigera nucleopolyhedrovirus

“…The large number of DEGs and noticeably higher numbers of down-regulated DEGs (718) GO and KEGG analysis were performed for the investigation of DEG enrichment. In the reported systems of NPV-insect interactions, genes with roles in the stress response, apoptosis, immunity, transcription and translation regulation, protein trafficking, signal transduction, energy generation, endocrine modulation and cytoskeleton rearrangement were primarily enriched and clustered (Bao et al, 2009;Chen et al, 2014;Gatehouse et al, 2009;Nguyen et al, 2013;Popham 15 et al, 2010;Sagisaka et al, 2010;Salem et al, 2011). In this study, genes termed in "catalytic activity" and "metabolic process" were primarily induced by infection with HearNPV, which might facilitate NPV infection and multiplication due to increased nutrition and energy supply through digestion from host storage.…”