The emergence of viruses in Coffee (Coffea arabica and Coffea canephora), the most widely traded agricultural commodity in the world, is of critical concern. The RNA1 (6552nt) of Coffee ringspot virus is organized into five open reading frames (ORFs) capable of encoding the viral nucleocapsid (ORF1p), phosphoprotein (ORF2p), putative cell-to-cell movement protein (ORF3p), matrix protein (ORF4p) and glycoprotein (ORF5p). Each ORF is separated by a conserved intergenic junction. RNA2 (5945nt), which completes the bipartite genome, encodes a single protein (ORF6p) with homology to RNA-dependent RNA polymerases. Phylogenetic analysis of L protein sequences firmly establishes CoRSV as a member of the recently proposed Dichorhavirus genus. Predictive algorithms, in planta protein expression, and a yeast-based nuclear import assay were used to determine the nucleophillic character of five CoRSV proteins. Finally, the temperature-dependent ability of CoRSV to establish systemic infections in an initially local lesion host was quantified.

Coffee ringspot virus (CoRSV) a member of the proposed genus "Dichorhavirus", was surveyed on commercial and research farms spanning an area responsible for the majority of Coffea arabica production in Brazil. Virus-infected plants were found at one hundred percent of locations (n = 45) sampled. All cultivars, regardless of cherry color, were found to serve as hosts, suggesting that there is limited resistance in commercially employed germplasm. Reverse transcription PCR analysis revealed that the virus is contained within symptomatic lesions, with little systemic spread throughout leaves. Phylogenetic analysis based on the ORF1 (nucleocapsid) gene identified a strong geo-spatial relationship among isolates, which clustered into three clades. Despite low genetic diversity among isolates, variation in symptom expression was observed in the experimental host Chenopodium quinoa. Our analyses support the hypothesis that the spread of CoRSV is constrained by the clonal expansion of thelytokous populations of Brevipalpus phoenicis. The widespread occurrence of this virus suggests that it is much more prevalent than previously thought.

The Sf9 and Sf21 cell lines derived from ovarian tissues of the wide-host-range phytophagous lepidopteranSpodoptera frugiperdaare widely used for research and commercial-scale production of recombinant proteins. These cell lines are chronically infected with a rhabdovirus (Sf-RV) that does not cause any overt cytopathic effects. We demonstrate that wild populations ofS. frugiperdain the eastern United States and Caribbean are infected with genetically diverse strains of Sf-RV and that this virus is also capable of infecting cells ofSpodoptera exigua,Heliothis subflexa, andBombyx mori. Feeding studies demonstrated the ability ofS. frugiperdalarvae to deposit Sf-RV onto human-consumed vegetables during feeding. Although no evidence for replication in two species of plant cells was detected, subcellular localization studies demonstrated that the Sf-RV nucleocapsid was targeted to plasmodesmata, while two forms of the accessory protein were differentiated on the basis of their ability to localize to nuclei. Collectively, the results from this study suggest that environmental exposure of humans to Sf-RV is likely to be commonplace and frequent, but its inability to replicate in plant or human cells suggests that there is no substantial risk to human health.IMPORTANCEInsect-derived cell lines are widely used commercially for the production of vaccines and protein-based pharmaceuticals. After decades of safe and beneficial use, it was a surprise to the biotechnology industry to discover an endemic rhabdovirus in Sf9 cells. This discovery was made possible only by the substantial advancements in DNA sequencing technologies. Given the public health concerns associated with many rhabdovirus species, several initiatives were undertaken to establish thatSpodoptera frugiperdarhabdovirus (Sf-RV) does not pose a threat to humans. Such actions include the generation of cell lines that have been cleared of Sf-RV. Given that Sf9 is derived from a moth whose larvae feed on human-edible foods, we explored the prevalence of Sf-RV in its wild and lab-grown populations, as well as its ability to be deposited on food items during feeding. Collectively, our data suggest that there is no overt risk from exposure to Sf-RV.