Submitted to: Viruses
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2011
Publication Date: 10/28/2011
Citation: Breitenbach, J.E., Shelby, K., Popham, H.J. 2011. Baculovirus induced transcripts in hemocytes from Heliothis virescens. Viruses. 3(11):2047-2064.
Interpretive Summary: Budworm larvae are caterpillars that cause heavy economic loss to many agricultural commodities in North America and are closely related to the Old World bollworm that is an economic pest worldwide. We have developed a library of DNA sequences from this pest moth’s genome that encodes over 103,000 different genes. These sequences were screened for changes in expression in response to insect baculovirus infection and several groups of genes were identified that changed significantly. This is a much larger library of sequences from this moth that change in response to baculovirus than previously available and will be used worldwide by researchers. We will use the information to study genes that influence the immune system of the budworm which will lead us to what control measures work best and which control measures the insect will become resistant to in a short time.
Technical Abstract: Using RNA-sequencing digital difference expression profiling methods we have assessed the gene expression profiles of hemocytes harvested from Heliothis virescens that were challenged with Helicoverpa zea single nucleopolyhedrovirus (HzSNPV). A reference transcriptome of hemocyte-expressed transcripts was assembled from 202 million 42-base tags by combining the sequence data of all samples, and the assembled sequences were then subject to BLASTx analysis to determine gene identities. We used the fully sequenced HzSNPV reference genome to align 477,264 Illumina sequence tags from infected hemocytes in order to document expression of HzSNPV genes at early points during infection. A comparison of expression profiles of control insects to those lethally infected with HzSNPV revealed differential expression of key cellular stress response genes and genes involved in lipid metabolism. Transcriptional regulation of specific insect hormones in baculovirus-infected insects was also altered. A number of transcripts bearing homology to retroviral elements that were detected add to a growing body of evidence for extensive invasion of errantiviruses into the insect genome. Using this method, we completed the first and most comprehensive gene expression survey of both baculoviral infection and host immune defense in lepidopteran larvae.