Submitted to: Journal of General Virology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/1/2005
Publication Date: 2/1/2006
Citation: Gundersen, D.E., Pedroni, M.J. 2006. Characterization and transcritptional analysis of protein tyrosine phosphatase (ptp) genes of the parasitoid glyptapanteles indiensis polydnavirus (gibv) in the parasitized host.. Journal of General Virology. 87(2):311-322. 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 wasps is enhanced by a virus, called a polydnavirus, that is injected along with the wasp egg into the host caterpillar pest. In the current paper, we have used modern molecular techniques to analyze and characterize the genetic components of one large segment of a certain polydnavirus to help understand how these components are made and how they may be involved in protecting the parasitic wasp egg and assisting the wasp survival. We found the genetic components were primarily enzymes that are regulators of other genetic components. These regulators are made soon after infection in the caterpillar. We also looked at parameters that may help us predict the existence of these components in other polydnaviruses. The information obtained will help explain how the virus assists the wasp's survival, which understanding may lead to new biocontrol strategies based on wasp disruption of insect pest immune systems. 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 (Braconidae, Hymenoptera) is an endoparasitoid of Lymantria dispar, gypsy moth. Expression of G. indiensis polydnavirus (GiBV)-encoded genes within the pest host results in inhibition of immune response, development, and alteration of physiology, enabling successful development of the parasitoid. Here, GiBV genome segment F (seg F), an 18.6 Kb segment encoding nine protein tyrosine phosphatase (PTP) and a single ankyrin repeat gene (ank), is analyzed. PTPs have presumed function as regulators of signal transduction, while ankyrin repeat genes are hypothesized to function in inhibition of NF-kB signaling in the parasitized host. In this study, transcription of each gene was mapped by 5’- and 3’-RACE (rapid amplification of cDNA ends) and temporal and tissue-specific expression examined in the parasitized host. No available parameters for gene prediction for polydnaviruses were ideal for accurate gene identification in this system. The mRNAs for each GiBV segF gene initiated between 31 and 199 base pairs upstream of the translation initiation codons. All were encoded in single open reading frames (ORFs), with the exception of PTP9, which was transcribed as a bicistronic message with an adjacent ankyrin repeat gene (ank). Rt-PCR indicated all GiBV segF PTPs were expressed early in parasitization and, for most, expression was sustained over the course of at least 7 days post parasitization, suggesting importance in both early and sustained virus-induced immunosuppression and alteration of physiology. Tissue-specific patterns of PTP expression of GiVB segF genes were variable, suggesting differing roles in facilitating parasitism.