Isolation and characterization of a novel cripavirus, the first Dicistroviridae family member infecting the cotton mealybug Phenacoccus solenopsis.

A new virus belonging to the family Dicistroviridae was identified in the hibiscus-infesting cotton mealybug Phenacoccus solenopsis. Using high-throughput sequencing (HTS) on an Illumina HiSeq platform, a single contig of the complete genome sequence was assembled. The authenticity of the sequence obtained by HTS was validated by RT-PCR and Sanger sequencing of the amplicons, which was also employed for the 3' untranslated region (UTR). The 5' UTR was sequenced using a rapid amplification of cDNA ends kit. A large segment encompassing the whole genome was amplified by RT-PCR using viral RNA extracted from mealybugs. A whole-genome nucleotide sequence comparison showed 89% sequence identity to aphid lethal paralysis virus (ALPV), covering a short segment of 44 bp. Pairwise amino acid sequence comparisons of the protein encoded by open reading frame (ORF) 2 with its counterparts in the GenBank database, showed less than 40% identity to several members of the genus Cripavirus, including ALPV. Phylogenetic analysis based on the deduced amino acid sequence of the ORF 2 protein showed that the new virus grouped with members of the genus Cripavirus. The intergenic region (IGR) internal ribosome entry site (IRES) showed the conserved nucleotides of a type I IGR IRES and had two bulge sites, three pseudoknots, and two stem-loops. Virus morphology visualized by transmission electron microscopy demonstrated spherical particles with a diameter of ~30 nm. This virus was the only arthropod virus identified in the sampled mealybugs, and the purified virus was able to infect cotton mealybugs. To the best of our knowledge, this is the first report of a Dicistroviridae family member infecting P. solenopsis, and we have tentatively named this virus Phenacoccus solenopsis virus (PhSoV).