University of Kentucky

Studies in Entomology: Study 2: In Vivo Integration of Campoletis sonorensis Ichnovirus Genome Segments Into Heliothis virescens DNA

Institution

University of Kentucky

Abstract

Polydnaviruses (PDVs) are a group of insect viruses that reside within certain parasitoid wasps. When parasitizing, these wasps inject an egg as well as PDV into caterpillar hosts. The PDV suppresses the caterpillar's immune system, thus allowing the wasp egg to develop. PDVs share an intimate relationship with their wasp host; they do not replicate outside of the wasp body and their genome is stably integrated into that of the wasp. The PDV relationship with their caterpillar host, however, is supposedly transient, and the genome persists only as circular segments. This view was challenged when certain polydnavirus segments were found to persist in PDV-exposed lepidopteran cells, stably integrating into their cell genome. To explore this phenomenon in vivo, we injected a sample of fourth instar Heliothis virescens moth larvae with the Campoletis sonorensis ichnovirus (CsIV), raised them to adulthood, extracted DNA, and screened for the presence of 11 CsIV segments, using PCR (Polymerase Chain Reaction). Ten out of eleven segments were detected in at least one adult. One persisting segment, G2, was further analyzed in order to find its integration site in the wasp genome (which may be related to integration sites in the lepidopteran genome) using Thermal Asymmetrical Interlaced (TAIL) PCR, a method that requires very little starting material. We seek to completely describe the segments of CsIV that persist in whole organisms, and to show whether or not integration is occurring. This research may be applicable to the development of new gene therapy and P element techniques.

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Studies in Entomology: Study 2: In Vivo Integration of Campoletis sonorensis Ichnovirus Genome Segments Into Heliothis virescens DNA

Polydnaviruses (PDVs) are a group of insect viruses that reside within certain parasitoid wasps. When parasitizing, these wasps inject an egg as well as PDV into caterpillar hosts. The PDV suppresses the caterpillar's immune system, thus allowing the wasp egg to develop. PDVs share an intimate relationship with their wasp host; they do not replicate outside of the wasp body and their genome is stably integrated into that of the wasp. The PDV relationship with their caterpillar host, however, is supposedly transient, and the genome persists only as circular segments. This view was challenged when certain polydnavirus segments were found to persist in PDV-exposed lepidopteran cells, stably integrating into their cell genome. To explore this phenomenon in vivo, we injected a sample of fourth instar Heliothis virescens moth larvae with the Campoletis sonorensis ichnovirus (CsIV), raised them to adulthood, extracted DNA, and screened for the presence of 11 CsIV segments, using PCR (Polymerase Chain Reaction). Ten out of eleven segments were detected in at least one adult. One persisting segment, G2, was further analyzed in order to find its integration site in the wasp genome (which may be related to integration sites in the lepidopteran genome) using Thermal Asymmetrical Interlaced (TAIL) PCR, a method that requires very little starting material. We seek to completely describe the segments of CsIV that persist in whole organisms, and to show whether or not integration is occurring. This research may be applicable to the development of new gene therapy and P element techniques.