ARS | Publication request: Novel double-stranded RNA viruses of plant-feeding insects encode a serine-alanine-proline rich protein and a polymerase distantly related to fungal viruses

Submitted to: American Society for Virology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: February 1, 2010
Publication Date: July 15, 2010
Citation: Spear, A., Sisterson, M.S., Yokomi, R.K., Stenger, D.C. 2010. Novel double-stranded RNA viruses of plant-feeding insects encode a serine-alanine-proline rich protein and a polymerase distantly related to fungal viruses. American Society for Virology Meeting Scientific Program. P.79.

Technical Abstract: Novel double stranded RNAs (~8 kbp) were isolated from the three cornered alfalfa hopper (Spissistilus festinus) and beet leafhopper (Circulifer tenellus), two plant-feeding hemipteran insect pests. Genome organization of the two new viruses, designated as Spissistilus festinus virus 1 (SpFV1) and Circulifer tenellus virus 1 (CiTV1), was similar. The presumptive positive-strand contained a leader sequence of ~600 nts followed by an open reading frame (ORF) encoding a serine-alanine-proline rich (SAP) protein. BLASTX searches using the SAP proteins as queries failed to return subjects with significant e values. Expression of the 3’-proximal RNA directed RNA polymerase (RdRp) appears to result from -1 ribosomal frameshifting. BLASTX searches using SpFV1 and CiTV1 RdRp as queries returned as subjects the RdRp core domains of totiviruses, chrysoviruses and an obscure plant-infecting virus (curcurbit yellows associated virus, CurYAV). In addition, SpFV1 and CiTV1 share a similar genome organization with a cluster of unclassified fungal dsRNA viruses (5’ SAP ORF followed by a 3’ RdRp ORF expressed via -1 ribosomal frameshift). Attempts to recover and observe SpFV1 and CiTV1 virions using various purification protocols were unsuccessful, suggesting that the genomes of these viruses were not encapsidated in conventional virus particles. Phylogenetic analysis of the RdRp core domains indicated that SpFV1, CiTV1, and CurYAV constitute a distinct lineage representing a new taxon of dsRNA viruses.