title: Stage-dependent expression of Chelonus inanitus polydnavirus genes in the host and the parasitoid.
abstract: Chelonus inanitus (Braconidae) is a solitary egg-larval parasitoid of Spodoptera littoralis (Noctuidae). Along with the egg it also injects polydnaviruses (CiV) and venom, which are prerequisites for successful parasitoid development. CiV protects the parasitoid from encapsulation by the host's immune system and induces a developmental arrest in the prepupal stage. The polydnavirus genome consists of several double-stranded circular DNA segments. Proviral DNA is integrated in the wasp's genome and virus replication is restricted to the wasp's ovary. Here, the analysis of eight CiV genes located on five different segments revealed four patterns of expression in the course of parasitization: early, late, persistent but variable, and early and late. The comparison between parasitized and CiV/venom only containing hosts indicated that the presence of the parasitoid larva modulates transcript levels. Haemocytes, fat body and nervous tissue contained viral transcripts, values being highest in haemocytes. Small amounts of CiV transcripts were also observed in parasitoid larvae and pupae, suggesting transcription from the proviral integrated form of viral DNA. This is the first comparative analysis of the expression patterns of several viral genes in both parasitized and CiV/venom only containing hosts over the entire period of parasitization, and it reveals intricate interactions between the parasitoid, the polydnavirus and the host.
authors.affiliation: Institute of Cell Biology, University of Berne, Baltzerstrasse 4, CH-3012 Bern, Switzerland.
authors.forename: Marianne
authors.initials: M
authors.lastname: Bonvin
authors.forename: Dejan
authors.initials: D
authors.lastname: Kojic
authors.forename: Fabian
authors.initials: F
authors.lastname: Blank
authors.forename: Marc
authors.initials: M
authors.lastname: Annaheim
authors.forename: Irene
authors.initials: I
authors.lastname: Wehrle
authors.forename: Stefan
authors.initials: S
authors.lastname: Wyder
authors.forename: Martha
authors.initials: M
authors.lastname: Kaeslin
authors.forename: Beatrice
authors.initials: B
authors.lastname: Lanzrein
mesh_terms: D000818:Animals; D004279:DNA, Viral / Q000235:genetics / Q000302:isolation & purification; D015967:Gene Expression Regulation, Viral; D006790:Host-Parasite Interactions; D006927:Hymenoptera / Q000254:growth & development / Q000502:physiology* / Q000821:virology; D007814:Larva; D010063:Ovum; D018071:Polydnaviridae / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011679:Pupa; D012367:RNA, Viral / Q000302:isolation & purification; D018411:Spodoptera / Q000469:parasitology*; D014158:Transcription, Genetic
chemical_list: D004279:DNA, Viral; D012367:RNA, Viral