Submitted to: Virus Genes
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/28/2007
Publication Date: 6/1/2008
Citation: Harrison, R.L., Popham, H.J. 2008. Genomic sequence analysis of a granulovirus isolated from the Old World bollworm, Helicoverpa armigera. Virus Genes. 36:565-581. Interpretive Summary: Insect pests cause billions of dollars of damage to crops each year. The use of chemical insecticides to control insect pests can have negative ecological, environmental, and health consequences. Baculoviruses are a group of insect viruses that can be used for biologically-based insect control without the problems of chemical insecticides. A more complete understanding of the genetic factors regulating baculovirus insecticidal activity is necessary for improving their scope and performance as biopesticides. In this study, the entire DNA sequence of a baculovirus isolated from the Old World bollworm was determined and analyzed. Features of the DNA sequence that may contribute to this virus’s insecticidal activity were documented. The information in this study provides clues for how to identify or develop baculovirus strains with enhanced insecticidal activity. Baculoviruses have a wide range of applications in addition to their use as biopesticides, and this study will be of interest to scientists in academia, government, and industry who work with this group of viruses.
Technical Abstract: The genome of a granulovirus isolated from the Old World bollworm, Helicoverpa armigera, was completely sequenced. The size of the Helicoverpa armigera granulovirus (HearGV) genome is 169,794 nt containing 179 open reading frames (ORFs), making it the second largest baculovirus genome analyzed to date. The genomes of HearGV and the Xestia c-nigrum GV (XecnGV) exhibit extensive sequence similarity and co-linearity, with both genomes containing the same nine homologous regions (hrs) with conserved structure and locations and sharing 167 open reading frames (ORFs). Pairwise analysis of Kimura-2-parameter nucleotide distances for the lef-8, lef-9, and granulin genes indicates that HearGV is more distantly related to XecnGV than other previously identified variants of XecnGV. Alignment of the HearGV and XecnGV genome sequences revealed that HearGV is missing approximately 16.6 kbp of XecnGV-homologous sequence and contains approximately 8.2 kbp of sequence not found in the XecnGV genome. The HearGV genome contains all 62 ORFs found in common among other fully-sequenced baculovirus genomes, and seven ORFs not found in other baculovirus genomes sequenced to date. One of the ORFs unique to HearGV (hear56) has homologues in two ascovirus genomes, while another two unique ORFs (hear75 and hear76) display significant sequence similarity to members of the polydnavirus Rep gene family. In addition to possessing ten ORFs with sequence similarity to baculovirus repeated ORFs (bro), the HearGV genome contains members of two other gene families with members in ascovirus, nucleopolyhedrovirus, and entomopoxvirus genomes.