Submitted to: Insect Biochemistry and Molecular Biology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/20/2003
Publication Date: 2/15/2003
Citation: Chen, Y., Higgins, J.A., Gundersen, D.E. 2004. Quantification of a glyptapanteles indiensis polydnavirus gene expression in its parasitized host, lymantria dispar by real-time quantitative rt-pcr. Insect Biochemistry and Molecular Biology. Interpretive Summary: Parasitic wasps have great potential for the control of moth species that are pests of agricultural crops and forests. The survival of many of these parasites is enhanced by a virus, called a polydnavirus, that is injected along with the wasp egg into the host caterpillar. In the current paper, we have used modern molecular techniques to analyze expression of a polydnavirus gene that may be involved in protecting the parasitic wasp egg and assisting the wasp survival. We found the protein associated with this virus gene was made soon after infection at a high level in the caterpillar pest hemolymph (insect blood). This knowledge may help us to understand how the virus assists in the wasp's survival, information which may lead to new biocontrol strategies based on wasp disruption of insect pest immune system. This information will be of interest to university and industry scientists who are interested in developing new virus-based strategies for use in pest control programs.
Technical Abstract: Glyptapanteles indiensis is a polydnavirus-carrying wasp that parasitizes the gypsy moth larvae. During oviposition, the wasp injects calyx fluid containing polydnavirus along with its eggs into the host. Within host, the expression of polydnavirus genes triggers a set of changes in host physiology, which are of critical importance for the survival of the wasp. In the present study, a G. indiensis polydnavirus (GiPDV) gene, designated GiPDV 1.1, was selected for gene expression analysis. The GiPDV 1.1 transcript was detected in host hemolymph 30 minutes post parasitization and continued to be detected for six days. The level of GiPDV 1.1 expression in the brain was lower than in the hemolymph and the speed of GiPDV 1.1 expression in the brain was also slower than in the hemolymph. Our findings suggest that GiPDV 1.1 could be a viral gene involved in early protection of parasitoid eggs from host cellular encapsulation. The variation in gene expression level and timing in the different host tissues post parasitization supports host regulation mechanism for polydnaviruses which determines gene expression at specific times or in specific tissues during parasitism.