Biological and molecular features of the relationships between Diadromus pulchellus ascovirus, a parasitoid hymenopteran wasp (Diadromus pulchellus) and its lepidopteran host, Acrolepiopsis assectella.

Abstract

Biological and molecular features of the relationships between Diadromus pulchellus ascovirus, a parasitoid hymenopteran wasp (Diadromus pulchellus) and its lepidopteran host, Acrolepiopsis assectella

Genomic Sequence of Spodoptera frugiperda Ascovirus 1a , an Enveloped, Double-Stranded DNA Insect Virus That Manipulates Apoptosis for Viral Reproduction

“…With respect to the last, the relationship we detected between SfAV-1a and Chilo IV, an iridovirus that infects lepidopterans, suggests that many genes coding for proteins involved in ascovirus vesicle formation or their homologs may have been acquired from a lepidopteran host, as CIV does not form such vesicles. An alternative hypothesis is that these genes originated from the genome of a parasitic wasp, such as the ichneumonid D. pulchellus, that transmits DpAV-4a, the genome of which has been detected in nuclei of its wasp vector without causing any apparent pathology (17). These hypotheses are clearly speculative and will be answered only upon more experimental research with ascovirus and the determination of full genomic sequences for several endoparasitic wasp and lepidopteran species.…”

“…In contrast, SfAV-1a has a narrow host range, apparently capable of replicating only in Spodoptera species. The most unusual ascovirus is DpAV-4a, which replicates in its wasp vector and is transmitted vertically to its lepidopteran host, in which it replicates much more extensively (17,18).…”

A viral caspase contributes to modified apoptosis for virus transmission

“…Our previous studies of the molecular evolution of ascoviruses indicate that these viruses evolved from insect iridoviruses (family Iridoviridae) and may be an evolutionary intermediate to the virus-like particles classified as ichnoviruses (family Polydnaviridae), which are vectored by parasitic wasps (Webb et al 2000;Federici and Bigot 2003;Stasiak et al 2003). It is therefore likely that the SfAV or one of its progenitors acquired this caspase gene from a lepidopteran or possibly a hymenopteran host, the only two types of insects in which ascoviruses are known to replicate (Federici et al 2000;Bigot et al 1997).…”

“…An interesting exception to this transmission pattern is the ascovirus that attacks pupae of the leak moth, Acrolepiosis assectella. The genome of this ascovirus is carried unintegrated in the nuclei of males and females of its wasp vector, Diadromus pulchellus, and virions are transmitted vertically during oviposition by the wasp, which is highly dependent on this virus for parasitic success (Bigot et al 1997).While the transmission of ascoviruses is unusual for an insect virus, the most novel feature of these viruses compared with all others is their reproductive cellular biology. After infecting a cell, these viruses initiate a cytopathology that resembles apoptosis, but in vivo differs significantly in several features.…”

“…An interesting exception to this transmission pattern is the ascovirus that attacks pupae of the leak moth, Acrolepiosis assectella. The genome of this ascovirus is carried unintegrated in the nuclei of males and females of its wasp vector, Diadromus pulchellus, and virions are transmitted vertically during oviposition by the wasp, which is highly dependent on this virus for parasitic success (Bigot et al 1997).…”