Complete genome sequence of a new polerovirus identified in Ageratum conyzoides.

A new polerovirus, designated as "ageratum virus 3" (AgV3), was detected in an Ageratum conyzoides plant in China. The complete genome sequence of AgV3 was determined using high-throughput sequencing, rapid amplification of cDNA ends, and Sanger sequencing of RT-PCR fragments. The organization of its single-stranded RNA genome of 5,652 nucleotides is typical of members of the genus Polerovirus in the family Solemoviridae, with seven putative open reading frames (ORFs 0-5 and ORF3a). The AgV3 genome shares the highest nucleotide sequence identity (65.7%) with that of cucurbit aphid-borne yellows virus (genus Polerovirus). Sequence comparisons of the gene products of AgV3 to those of its closest relatives revealed that all of them, with the exception of the ORF3a protein, had amino acid sequence identity values that were below the threshold for demarcation for species within the genus Polerovirus established by the International Committee of Taxonomy of Viruses (ICTV), suggesting that AgV3 is a new member of the genus Polerovirus. Phylogenetic analysis based on P1-P2 and coat protein amino acid sequences also indicated that AgV3 is a novel polerovirus.