Infectious transcripts of an asymptomatic panicovirus identified from a metagenomic survey

A new panicovirus was identified from a metagenomic survey of plant viruses in the Tallgrass Prairie Preserve (TPP), Osage County, Oklahoma, USA. Thin paspalum asymptomatic virus (TPAV) was isolated from Paspalum setaceum var. muehlenbergii. The complete 4195 nucleotide sequence encodes six proteins of 44, 109, 8, 6.8, 26, and 15 kDa, whose genes are similar in size and location to those of panicum mosaic virus (PMV) and cocksfoot mild mosaic virus (CMMV). Infectious transcripts made from cDNAs of the 2005 isolate were used for initial host range analyses. Of the 11 tested grasses, only Paspalum setaceum (var. stramineum), Setaria italica, and Setaria viridis were hosts, producing asymptomatic infections, and Nicotiana benthamiana was not infected. Protein and RNA alignments indicate that TPAV is more closely related to PMV than CMMV. RNA alignments and structure predictions indicate that TPAV and CMMV have conserved eight structural elements previously predicted or analyzed for PMV. The initial TPP specimen also contained RNAs related to alphacryptoviruses. Partial sequences of RNA1 (∼35%) and RNA2 (∼40%) of putative thin paspalum cryptic virus were obtained. These represent the first sequences for a putative grass-infecting alphacryptovirus.