Complete Genome Sequence and Molecular Characterization of Homalodisca coagulata virus-1, a novel virus discovered in the glassy-winged sharpshooter (Hemiptera: Cicadellidae)

• Author(s): Cave, R.; Hunnicutt, L.; Hunter, Wayne; Mozoruk, J.; Powell, C.;
• Abstract: Few viral pathogens of leafhoppers have been discovered or examined as potential microbial control agents. The recent discovery of HoCV-1 a virus which infects and kills glassy-winged leafhoppers, GWSS, Homalodisca coagulata, (Hemiptera: Cicadellidae) provides a unique opportunity to better understand viral/leafhopper interactions. GWSS is an important vector of Xylella caused diseases. The best known example is Pierces Disease of grapes. However, the bacterial complex of Xylella fastidiosa, also causes many different diseases which affect fruit trees and woody crops. The complete nucleotide sequence of this novel single-stranded RNA virus, Homalodisca coagulata virus-1 (HoCV-1) has been determined. In silico analysis of HoCV-1 revealed a 9321 nt polyadenylated genome encoding two large open reading frames (ORF1 and ORF2) separated by a 179 nt intergenic region (IGR). The deduced amino acid sequence of the 5'-proximal ORF (ORF1, nt 420-5807) exhibited conserved core motifs characteristic of the helicases, cysteine proteases, and RNA-dependent RNA polymerases of other insect-infecting picorna-like viruses. A structural model created using M-FOLD exposed a series of stem-loop (SL) structures immediately preceding the second ORF which are analogous to an internal ribosome entry site (IRES), suggesting that ORF2 begins with a noncognate GCA triplet rather than the canonical AUG. This 3' ORF2 (nt 5987-8740) showed significant similarity to the structural proteins of members of the family Dicistroviridae, particularly those belonging to the genus Cripavirus. Evidence demonstrating relatedness of these viruses regarding genome organization, amino acid sequence similarity, and putative replication strategy substantiate inclusion of HoCV-1 into this taxonomic position. HoCV-1 as the first virus reported from GWSS is being evaluated for potential use as a microbial biological control agent to augment current management strategies against the GWSS.
• Publication Date: Jan 2006
• Journal: Virology