Genome scale analysis of differential mRNA expression of Helicoverpa zea insect cells infected with a H. armigera baculovirus

- The genome-scale expression study of the Helicoverpa armigera-H. zea is presented.
- mRNA level of both host and virus genes at early and late infection was measured.
- Insights on systemic production of H. armigera virus mRNA and DNA were obtained.
- Data normalization at late infection used spike-in controls not quantile approaches.
- New host genes/pathways important for H. armigera virus infection were identified.

Knowledge of baculovirus-insect host interactions at a genome-scale level is important for developing a number of baculovirus-based applications, but the gathering of such knowledge is hindered by the lack of genomic sequences in most insect hosts. In this study, expression kinetics of 24,206 Helicoverpa zea insect transcripts and 134 Helicoverpa armigera nucleopolyhedrovirus (HearNPV) genes at 0, 12, 24 and 48 h post-infection (hpi) were simultaneously analyzed using microarrays, which were developed from sequences obtained by deep transcriptome sequencing. Host genes in pathways important for infection such as those for energy generation, anti-viral peptides, apoptosis, detoxification, DNA polymerase activities, RNA polymerase activities, translation initiation, protein processing and cell cycle arrest were identified. Differential expression was linked to changes in the number of intracellular and extracellular viral genomes and occlusion bodies. The first comprehensive elucidation of HearNPV-H. zea expression kinetics was obtained.