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Title: Genomic sequence analysis of a nucleopolyhedrovirus isolated from the diamondback moth, Plutella xylostella

Author
item Harrison, Robert - Bob
item Lynn, Dwight

Submitted to: Journal of General Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/27/2007
Publication Date: 12/1/2007
Citation: Harrison, R.L., Lynn, D.E. 2007. Genomic sequence analysis of a nucleopolyhedrovirus isolated from the diamondback moth. Virus Genes. 35:857-873.

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. However, the success of baculoviruses as control agents is partially limited by the narrow range of insect pests against which they are effective. 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 diamondback moth was determined and analyzed. Features of the DNA sequence that may contribute to a high level of insecticidal activity against the diamondback moth were documented. In particular, an unusual form of a baculovirus gene involved in viral DNA and protein synthesis was identified in the diamondback moth virus DNA sequence. The information in this study provides clues for how to 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 CL3 plaque isolate of Plutella xylostella multiple nucleopolyhedrovirus (PlxyMNPV-CL3) exhibits a high degree of genetic similarity with the Autographa californica MNPV but is significantly more virulent against the diamondback moth, P. xylostella, than AcMNPV. To identify genetic differences between PlxyMNPV-CL3 and AcMNPV that may account for the difference in virulence against P. xylostella, the genome sequence of the CL3 plaque isolate of PlxyMNPV was determined and compared to the genome sequence of AcMNPV isolate C6. The PlxyMNPV genome is 134,417 bp, 523 bp larger than the AcMNPV-C6 genome, and the nucleotide sequence is almost completely co-linear with that of AcMNPV-C6. Of the 152 open reading frames (ORFs) identified in PlxyMNPV, 151 had homologues in AcMNPV-C6, with a mean amino acid sequence identity of 98.5%. The PlxyMNPV genome possessed two features previously reported for other variants of AcMNPV: (1) an extra baculovirus repeated orf (bro) sequence located between the plxy29/ac30 and sod ORFs, and (2) the deletion of the AcMNPV pnk/pnl polynucleotide kinase/ligase gene. In addition, an 817-bp insert of unknown origin located between the fp25K and lef-9 genes was discovered. This insert contained two small ORFs and was detected in both tissue culture- and larvae-derived PlxyMNPV DNA by PCR. Finally, the PlxyMNPV-CL3 ie2 gene encodes a product with a low level (37.3%) of amino acid sequence identity with the AcMNPV-C6 ie2 product. PlxyMNPV-CL3 apparently acquired this variant ie2 gene by recombination with an undescribed nucleopolyhedrovirus.