Pelarspovirus, a proposed new genus in the family Tombusviridae

Abstract

Currently, the family Tombusviridae encompasses thirteen viral genera that contain single-stranded, positive-sense RNA genomes and isometric virions; the exception being the genus Umbravirus, whose members do not encode a coat protein (CP). A new genus, tentatively named Pelarspovirus, is proposed to be added to this family and would include five members, with Pelargonium line pattern virus recommended as the type species. Viruses assigned to this proposed genus have monopartite genomes encoding five open reading frames (ORFs) that include two 5 0 -proximal replication proteins, two centrally located movement proteins (MP1 and MP2) and a 3 0 -proximal CP that, at least for pelargonium line pattern virus (PLPV), has been shown to act also as suppressor of RNA silencing. Distinguishing characteristics of these viruses include i) production of a single, tricistronic subgenomic RNA for expression of MP and CP genes, ii) presence of a non-AUG start codon (CUG or GUG) initiating the MP2 ORF, iii) absence of AUG codons in any frame between the AUG initiation codons of MP1 and CP genes, and iv) sequence-based phylogenetic clustering of all encoded proteins in separate clades from those of other family members.

Exploration of the virome of the European brown shrimp (Crangon crangon)

“…Tombusviridae, is a family of viruses mainly infecting plants [49]. To our knowledge, there are no reports of crustacean viruses, which were assigned to this family, except for the ones described by Shi et al [25].…”

A novel block of plant virus movement genes

“…Among the transport systems of plant RNA viruses encoding more than one MP, the double gene block (DGB) is the shortest gene module, which encodes two small non-enzymatic MPs (Hull, 2002). The DGB is characteristic of the many Tombusviridae genera, including Carmovirus, Machlomovirus, Alphanecrovirus, Betanecrovirus, Panicovirus, Avenavirus, Macanavirus, Galantivirus and Pelarspovirus (Scheets et al, 2015). The first DGB gene encodes the RNA-binding protein believed to form transport ribonucleoproteins (RNPs), whereas the second DGB gene codes for a transmembrane protein, which is targeted to PD in a Golgi-and actin-dependent manner (Genov es et al, 2010;Navarro et al, 2006).…”

Evidence supporting a premature termination mechanism for subgenomic RNA transcription in Pelargonium line pattern virus: identification of a critical long-range RNA–RNA interaction and functional variants through mutagenesis

“…In addition, the MP2 gene of PLPV presents a non-AUG initiation codon instead of the canonical AUG of MP2 gene of carmoviruses, and moreover, PLPV lacks any AUG triplet between the MP1 AUG and CP AUG initiation codons while carmoviruses have 1-8 AUGs in the equivalent region. These distinctive traits are shared by four other small isometric (+)-RNA viruses that are structurally and phylogenetically related to PLPV, which has led to the proposal of their inclusion into a new genus, tentatively named Pelarspovirus, within the family Tombusviridae, with the recommendation of PLPV as type species (Castaño & Hern andez, 2005;Kinard & Jordan, 2002;Scheets et al, 2015).…”