Polydnavirus DNA is integrated in the DNA of its parasitoid wasp host.

Abstract

The polydnavirus Campolekis sonorensis virus (CsV) is present in the oviducts of all adult C. sonorensis female wasps and appears to be required for these wasps to parasitize hosts successfully. Physical mapping, Southern blot analysis, and nucleotide sequence analysis demonstrate that the viral DNA B-specific sequences in cloned wasp DNA are colinear with viral genomic segment DNA B from nucleocapsids and are covalently linked to nonviral wasp sequences. Integrated DNA B terminates in 59-nucleotide imperfect direct repeats, but a single repeat exists in the extrachromosomal superhelical viral DNA B. Sequences near each junction form imperfect inverted repeats with sequences near the ends of an internal viral 540-base-pair repeat element gene. CsV appears to be the frst documented integrated, nonretroviral DNA virus of insects and probably is vertically transmitted as a provirus.

Vertically transmitted viral endosymbionts of insects: do sigma viruses walk alone?

“…A curious exception to this pattern are polydnaviruses, which are transmitted as proviruses integrated into the genomes of ichneumonid and braconid parasitoid wasps, but are still able to produce viral particles [12]. The ancestor of polydnaviruses in braconid wasps was a nudivirus, a genus of arthropod viruses with double-stranded DNA genomes [13], which integrated into the wasp genome [14]. The viral genome is copied into multiple double-stranded DNA circles and packaged into viral particles that are injected into the lepidopteran larval hosts that the wasps parasitize [12].…”

Microplitis demolitor polydnavirus induces apoptosis of a specific haemocyte morphotype in Pseudoplusia includens

“…Most of these wasps parasitize the larval stage of Lepidoptera and their associated polydnaviruses appear to share a common life cycle. Viral DNAs from at least one ichneumonid polydnavirus are integrated into the genome of male and female wasps and are likely to be transmitted vertically as a provirus (Fleming & Summers, 1991;Xu & Stoltz, 1991). Whether viral DNAs are integrated in braconids is unknown, although genetic studies with Cotesia melanoscela are consistent with chromosomal inheritance (Stoltz, 1993).…”

Interactions Between Nucleopolyhedroviruses and Polydnaviruses in Larval Lepidoptera

“…Most of the known polydnaviruses are carried by wasps that parasitize larval Lepidoptera, in subfamilies of the Ichneumonidae (these polydnaviruses are termed ichnoviruses) and Braconidae (the bracoviruses) (Stoltz & Vinson, 1977;Fleming & Summers, 1991;Stoltz & Whitfield, 1992;Webb & Strand, 2005). At this time, known polydnavirus carrier wasps occur only in the braconid subfamilies Cardiochilinae, Cheloninae, Mendesellinae, Khoikhoiinae, Miricinae and Microgastrinae, and ichneumonid subfamilies Campopleginae and Banchinae (Table 1) LaPointe et al, 2007;Whitfield & O'Connor, 2012).…”