Genome Analysis of Dasineura jujubifolia Toursvirus 2, A Novel Ascovirus
So far, ascoviruses have only been identified from Lepidoptera host insects and their transmission vectors—endoparasitic wasps. Here, we reported the first finding of a complete novel ascovirus genome from a Diptera insect, Dasineura jujubifolia. Initially, sequence fragments with homology to ascoviruses were incidentally identified during metagenomic sequencing of the mitochondria of D. jujubifolia (Cecidomyiidae, Diptera) which is a major pest on Ziziphus jujuba. Then a full circular viral genome was assembled from the metagenomic data, which has an A+T percentage of 74% and contains 142,600 bp with 141 open reading frames (ORFs). Among the 141 ORFs, 37 were conserved in all sequenced ascoviruses (core genes) including proteins predicted to participate in DNA replication, gene transcription, protein modification, virus assembly, lipid metabolism and apoptosis. Multi-gene families including those encode for baculovirus repeated open reading frames (BROs), myristylated membrane proteins, RING/U-box E3 ubiquitin ligases, and ATP-binding cassette (ABC) transporters were found in the virus genome. Phylogenetic analysis showed that the newly identified virus belongs to genus Toursvirus of Ascoviridae, and is therefore named as Dasineura jujubifolia toursvirus 2 (DjTV-2a). The virus becomes the second reported species of the genus after Diadromus pulchellus toursvirus 1 (DpTV-1a). The genome arrangement of DjTV-2a is quite different from that of DpTV-1a, suggesting these two viruses separated in an early time of evolution. The results suggest that the ascoviruses may infect a much broader range of hosts than our previous knowledge, and shed lights on the evolution of ascoviruses and particularly on that of the toursviruses.
KeywordsDasineura jujubifolia toursvirus 2 (DjTV-2a) Ascovirus Toursvirus
This work was supported by the International Science and Technology Cooperation Program of Xinjiang Construction Corps (Grant No. 2017BC004) and the National Natural Science Foundation of China (Grant No. 31900154).
HX and MY conceived and designed the experiments. HX performed the experiments. JW, ZH, GHH analysis the data. JW, FD, ZH, GHH, and MY wrote the manuscript. All authors read and approved the final manuscript.
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Conflict of interest
The authors declare that they have no conflict of interests.
Animal and Human Rights Statement
This article does not contain any studies with human or animal subjects performed by any of the authors.
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