Putative Replication Intermediates in Endornavirus, a Novel Genus of Plant dsRNA Viruses

Abstract

Oryza sativa endornavirus (OSV) belongs to a new genus (Endornavirus) and family (Endoviridae) with members containing large double-stranded RNA (dsRNA) replicons with plasmid-like properties. Analysis of products obtained from in vitro reaction of the OSV RNA-dependent RNA polymerase revealed a rapid increase of a population of the non-coding strand RNA molecules with a head-to-tail composition. Northern hybridization of total RNA from OSV-carrier cells with riboprobes specific for the coding strand RNA, revealed two types of RNA molecules (i) with a site specific nick and (ii) full-length unnicked molecules. Quantitative analyses of these RNAs showed about 50-fold higher amounts of full-length unnicked molecules in cultured cells in which the OSV copy number increases compared with those found in the seedling cells. Both the head-to-tail linked non-coding strand and the full-length coding strand molecules were also found in wild rice and broad beans infected with other endornaviruses indicating that the presence of these unique types of RNA molecules should be considered as a characteristic feature of Endoviridae .

Metagenomic analysis of viruses in reclaimed water

“…Currently, four species of dsRNA viruses with plasmid‐like properties found in some rice and bean species have been classified by the International Committee on Taxonomy of Viruses as members of the Endornavirus genus (Gibbs et al ., 2005). In addition, double‐stranded RNA viruses with plasmid‐like properties have been found in plants, algae, fungi, protozoa and insects and, thus, endorna‐like viruses may be widely distributed among eukaryotes (Horiuchi and Fukuhara, 2004; Fukuhara et al ., 2006; Osaki et al ., 2006).…”

Evolution of and Horizontal Gene Transfer in the Endornavirus Genus

“…These ORFs normally encode a single polypeptide that is thought to be processed by a proteinase, and the genome contains conserved motifs, including an RNA-dependent RNA polymerase (RdRp) and viral RNA helicases (Hel) [20]. Endornaviruses seem not to form true virions and are usually present at a low copy number [21]. These viruses have been found in plants, fungi, and protists [22].…”

Extracción y purificación de dsRNAs largos de plantas infectadas con virus y hongos; aplicación en la detección e identificación de virus

“…In most plants and fungi infected with RNA viruses, dsRNAs can be found as part of: 1) genomic segments of dsRNA viruses; 2) replicative forms and replicative intermediates of single-stranded RNA viruses (ssRNA) (Buck, 1999;Horiuchi and Fukuhara, 2004;Jackson et al, 1971;Libonati et al, 1980;Nuss and Koltin, 1990;Zelcer et al, 1981); 3) subgenomic viral RNAs (sgRNAs) (Condit and Fraenkel-Conrat, 1979;Osman and Buck 1990); 4) satellite viruses (Klein and Reichman, 1970;Hillman et al, 2000;; 5) satellite RNAs (Demler and de Zoeten, 1989;Liu et al, 2015); and 6) defective interfering RNAs (Burgyan et al, 1989;Hillman et al, 2000). Serological detection of dsRNAs hongos y bacteriófagos (Libonati et al, 1980).…”

“…During replication in host cells, ssRNA viruses generate double-stranded replicative forms (RF) which consist of fully base-paired RNA molecules of the genomic RNA and replicative intermediates (Buck, 1999). They have been shown to occur in Tobacco mosaic virus (TMV) and Tobacco ringspot virus infected plants (Buck 1999;Derrick, 1978;German and de Zoeten, 1975;Jackson et al, 1971;Zelcer et al, 1981) and Oryza sativa endornavirus (Horiuchi and Fukuhara, 2004) among others. Many ssRNA viruses generate subgenomic RNAs (sgRNAs) to express internal open reading frames.…”