Family: Ascoviridae

Genus: Toursvirus

Distinguishing features

Currently, there is only one species within this genus, Diadromous pulchellus toursvirus. The single known member of this species, Diadromous puchellus toursvirus (DpTV) is transmitted by the parasitoid wasp Diadromous pulchellus, which typically parasitizes pupae of the lepidopteran family Yponomeutidae. 

Virion

Morphology

Virions of Toursvirus are flattened rice-grain shape, and fragile relative to members of the genus Ascovirus. Virions are typically 220 nm long and 150 nm wide. 

Nucleic acid

Genome consists of a circular dsDNA of about 119 kbp with a GC% of 49.7 encoding 119 putative genes. The genome of DpTV is the smallest within the family Ascoviridae. 

Proteins

Eleven virion proteins are shared with members of the genus Ascovirus (Bigot et al., 2009). 

Genome organization and replication

The genome of the only member of this genus, DpTV (Bigot et al., 2009) has been sequenced. Replication is largely similar to members of the genus Ascovirus. 

Biology

Host range

Similar to ascoviruses, toursvirus DpTV, is transmitted by a parasitoid wasp, Diadromus pulchellus. DpTV infection has mainly been found in the pupae of members of the lepidopteran family of Yponomeutidae. The virus also has a limited replication in the ovaries of the female wasp and is vertically transmitted as extrachromosomal DNA. Compared to the lepidopteran host, replication of DpTV in the parasitoid wasp is very limited (Bigot et al., 1997). 

Species demarcation criteria

 Not applicable.