Submitted to: Virus Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 19, 2011
Publication Date: February 2, 2012
Citation: Spear, A., Sisterson, M.S., Stenger, D.C. 2012. Reovirus genomes from plant-feeding insects represent a newly discovered lineage within the family Reoviridae. Virus Research. 163:503-511. Interpretive Summary: Two new reoviruses with genomes comprised of 10 double-stranded RNA segments were discovered infecting the threecornered alfalfa hopper (Spissistilus festinus reovirus, SpFRV) and the angulate leafhopper (Acinopterus angulatus reovirus, AcARV). Nucleotide sequences of the complete genome of SpFRV and the AcARV genome segment encoding the RNA directed RNA polymerase (RdRp) were determined. SpFRV and ACARV were most closely related to each other but only distantly related to all other reovirus species. Phylogenetic analysis of the RdRp indicated that SpFRV and AcARV constitute a new genus of the subfamily Spinareovirinae in the family Reoviridae. Both virus species were detected in field populations of their respective insect hosts sampled in the San Joaquin Valley of California during 2009-2011 and may have utility as biological control agents of hemipteran insect pests of crops.
Technical Abstract: A complex set of double-stranded RNAs (dsRNAs) was isolated from threecornered alfalfa hopper (Spissistilus festinus), a plant-feeding hemipteran pest. A subset of these dsRNAs constitute the genome of a new reovirus, provisionally designated Spissistilus festinus reovirus (SpFRV). SpFRV was present in threecornered alfalfa hopper populations in the San Joaquin Valley of California, with incidence ranging from 10% to 60% in 24 of 25 sample sets analyzed. The 10 dsRNA segments of SpFRV were completely sequenced and shown to share conserved terminal sequences (5’-AGAGA and CGAUGUUGU-3’) of the positive-sense strand that are distinct from known species of the family Reoviridae. Comparisons of the RNA directed RNA polymerase (RdRp) indicated SpFRV is most closely related (39.1% amino acid identity) to another new reovirus infecting the angulate leafhopper (Acinopterus angulatus) and provisionally designated Acinopterus angulatus reovirus (AcARV). The RdRp of both viruses was distantly related to Raspberry latent virus RdRp at 27.0% (SpFRV) and 30.0% (AcARV) or Rice ragged stunt virus RdRp at 26.2% (SpFRV) and 29.0% (AcARV) amino acid identity. SpFRV segment 6 encodes a protein containing two NTP binding motifs that are conserved in homologues of reoviruses in the subfamily Spinareovirinae. RdRp phylogeny confirmed that SpFRV and AcARV are sister taxa sharing a most recent common ancestor. Although four additional SpFRV segments encode homologues of reovirus structural proteins, no homologues were identified for proteins encoded by four other segments. Collectively, the low level of sequence identity with other reoviruses, similar segment terminal sequences, RdRp phylogeny, and host taxa indicate that SpFRV and AcARV may be considered members of a proposed new genus of the family Reoviridae, with SpFRV assigned as the type species.