Tepovirus, a novel genus in the family Betaflexiviridae

Abstract

Tepovirus is a new monotypic genus of plant viruses typified by potato virus T (PVT), a virus with helically constructed filamentous particles that are 640 nm long, previously classified as unassigned species in the family Betaflexiviridae. Virions have a single-stranded positive-sense polyadenylated RNA genome that is 6.5 kb in size, and a single type of coat protein with a size of 24 kDa. The viral genome contains three slightly overlapping ORFs encoding, respectively, the replication-related proteins (ORF1), a putative movement protein of the 30 K type (ORF2) and the coat protein (ORF3). Its structure and organization (number and order of genes) resembles that of trichoviruses and of citrus leaf blotch virus (CLBV, genus Citrivirus) but has a smaller size. Besides potato, the primary host, PVT can experimentally infect herbaceous hosts by mechanical inoculation. No vector is known, and transmission is through propagating material (tubers), seeds and pollen. PVT has a number of biological, physical and molecular properties that differentiate it from betaflexiviruses with a 30K-type movement protein. It is phylogenetically distant from all these viruses, but least so from grapevine virus A (GVA), the type member of the genus Vitivirus, with which it groups in trees constructed using the sequences of all of the genes.

Plant to Plant Movement

“…Mink, 1993;Card et al 2007. b H, horizontal;V, vertical. e Rubino et al (2012). d Nakamura et al (2011).…”

Characterization of New Isolates of Apricot vein clearing-associated virus and of a New Prunus-Infecting Virus: Evidence for Recombination as a Driving Force in Betaflexiviridae Evolution

“…Two genera, Carlavirus , Foveavirus , and some unassigned members possess a set of three open reading frames (ORFs) collectively known as the triple gene block (TGB), involved in cell-to-cell movement. The remaining genera, Citrivirus , Capillovirus , Trichovirus , Vitivirus , and the recently accepted genus Tepovirus have a single movement protein (MP) belonging to the "30K-like" superfamily [24–25]. In the genera Vitivirus and Carlavirus , and in some members of the genus Trichovirus , an additional ORF is present 3’ of the coat protein (CP), and encodes an RNA-binding protein with a zinc-ribbon motif, identified as a suppressor of silencing in Grapevine virus A [26].…”

Identification of a novel member of the family Betaflexiviridae from the hallucinogenic plant Salvia divinorum

“…In addition to REP, MP, and CP, the SdRV1 genome was predicted to have an additional fourth ORF encoding a 120 aa NBP. NBP is commonly found in viruses of the genera Prunevirus, Vitivirus, and Carlavirus (Adams et al, 2012;Rubino et al, 2012;Veerakone et al, 2018), but not in the genus Citrivirus. Among these viruses, only pruneviruses have the same genome organization as SdRV1, implying a possible affiliation between SdRV1 and pruneviruses (Fig.…”

“…ORF1 encodes a replicase polyprotein (REP), which has viral methyltransferase, 2OG-Fe(II) oxygenase superfamily, viral RNA helicase, and RNA-dependent RNA polymerase (RdRp) domains. ORF2 and ORF3 encode a movement protein (MP) and a coat protein (CP), respectively (Adams et al, 2012;Rubino et al, 2012;Chavan et al, 2013;Marais et al, 2015). Viruses of the genus Prunevirus have four ORFs encoding REP, MP, CP, and a nucleic acidbinding protein (NBP) (Veerakone et al, 2018).…”