Characterization of a Novel RNA Virus Discovered in the Autumnal Moth Epirrita autumnata in Sweden

de Miranda, Joachim R.; Hedman, Harald; Onorati, Piero; Stephan, Jörg; Karlberg, Olof; Bylund, Helena; Terenius, Olle

In this manuscript, we describe the discovery and a limited set of molecular features of a novel 10 kb RNA virus that was assembled from transcriptome data of a diseased E. autumnata larva from the 2012-2013 geometrid outbreak in northern Fennoscandia. Subsequent screening of an extensive set of natural samples revealed that the virus could not be detected in either larvae (except for the original transcriptome sample) or pupae of both E. autumnata and O. brumata, and that it could be detected in only four adult E. autumnata, collected from three different sites. The dispersed distribution, generous titers, and clear evidence for virus replicative-strand intermediates indicate that adult E. autumnata are a true host of the virus, while the absence of the virus or its replication intermediates from all pupae and all but one larva suggests that these are not hosts. Since the adults live only a few weeks, are not very mobile, and do not feed or defecate, the persistence of Abisko virus in the adult autumnal moth population is difficult to explain unless other transmission routes or hosts are involved. The genome organization and phylogenetic analyses identify Abisko virus most closely with the negeviruses, a newly described group of insect-infecting viruses [6, 7] , but with sufficient uncertainty to leave both its classification and primary hosts status in doubt. Consequently, we decided to conservatively name the virus after the place it was found (Abisko), following the convention used for its closest relatives, the negeviruses, but leave its classification otherwise unassigned.