ICTV Virus Taxonomy Profile: Potyviridae 2022.

The family Potyviridae includes plant viruses with single-stranded, positive-sense RNA genomes of 8-11 kb and flexuous filamentous particles 650-950 nm long and 11-20 nm wide. Genera in the family are distinguished by the host range, genomic features and phylogeny of the member viruses. Most genomes are monopartite, but those of members of the genus Bymovirus are bipartite. Some members cause serious disease epidemics in cultivated plants. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Potyviridae, which is available at ictv.global/report/potyviridae.

ICTV Virus Taxonomy Profile: Alphaflexiviridae.

The family Alphaflexiviridae includes viruses with flexuous filamentous virions that are 470-800 nm in length and 12-13 nm in diameter. Alphaflexiviruses have a single-stranded, positive-sense RNA genome of 5.5-9 kb. They infect plants and plant-infecting fungi. They share a distinct lineage of alphavirus-like replication proteins that is unusual in lacking any recognized protease domain. With a single exception, cell-to-cell and long-distance movement is facilitated by triple gene block proteins in plant-infecting genera. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Alphaflexiviridae, which is available at www.ictv.global/report/alphaflexiviridae.

An annotated list of plant viruses and viroids described in Brazil (1926-2018) / Lista comentada de vírus e viróides de planta descritos no Brasil (1926-2018)

Abstract: A list of plant species, in alphabetical order by their scientific name, and the viruses found naturally infecting them in Brazilian territory, with some comments, was prepared . The production of such a list was based on a yearly catalog of publications on plant viruses collected by the author, from 1926 to 2018. Listed species of viruses were those recognized by the International Committee on Taxonomy of Viruses (ICTV), but also those characterized and still waiting official recognition, were included. Several cases of putative viral diseases were listed for historical reasons expecting to raise interest for their clarification. This list includes 345 plants species belonging to 74 families naturally infected by plant viruses in Brazil. Fabaceae and Asteraceae had most virus-infected species, respectively 49 and 36. Until 2018, a total of 213 plant virus and 6 viroid species belonging to 57 genera and 22 families and 6 orders, officially recognized by ICTV, were found naturally infecting these plants. Begomovirus and Potyvirus genera have most representatives, with 45 and 42 species, respectively. There are 59 characterized plant viruses, up to species level, described in Brazil waiting for the inclusion in the ICTV Master Species List. One hundred and thirteen viruses were identified up to genus level but still uncharacterized, while four putative isometric viruses and eleven presumptive viral diseases ("unidentified") are included in the list. A reverse catalog, listing viruses and the plant species in which they were found is also included.

Resumo: Esta publicação consiste em uma listagem de espécies de plantas, em ordem alfabética de seus nomes científicos, e dos vírus que foram encontrados naturalmente infetando-as em território brasileiro, com alguns comentários. O preparo de tal lista foi basedo nas publicações sobre vírus de plantas e as doenças que eles causam, colecionadas pelo autor de 1926 a 2018. Os vírus listados incluem aqueles já oficialmente reconhecidos pelo International Committee on Taxonomy of Viruses (ICTV), constantes do "Master Species List 2018". Também estão incluídos vírus já caracterizados, aguardando oficialização pelo ICTV, e outros casos de possíveis viroses, cujo agente causal ainda não se acha adequadamente caracterizado. A listagem inclui 345 espécies de plantas, pertencentes a 74 famílias, que foram encontradas naturalmente infetadas por diferentes vírus. Fabáceas e Asteráceas foram as famílias que tiveram mais espécies infetadas por vírus, respectivamente 49 e 36. Até 2018, 213 espécies de vírus e 6 de viróides, pertencentes a 57 gêneros e 22 famílias e 6 ordens, oficialmente reconhecidas pelo ICTV, acham-se descritas no Brasil. Os gêneros Begomovirus e Potyvirus têm mais espécies representadas, com 45 e 42 respectivamente. Além das espécies identificadas e aceitas pelo ICTV, foram incluídas na lista 59 possíveis espécies que ainda aguardam oficialização, 113 vírus identificados a nível de gênero, quatro possíveis vírus isométricos e onze presumíveis viroses, de agentes etiológicos não confirmados. Foi incluída também uma lista reversa, com catalogação dos vírus e viróides descritos no Brasdil e suas respectivas plantas hospedeiras.

Two novel circo-like viruses detected in human feces: complete genome sequencing and electron microscopy analysis.

The application of viral metagenomic techniques and a series of PCRs in a human fecal sample enabled the detection of two novel circular unisense DNA viral genomes with 92% nucleotide similarity. The viruses were tentatively named circo-like virus-Brazil (CLV-BR) strains hs1 and hs2 and have genome lengths of 2526 and 2533 nucleotides, respectively. Four major open reading frames (ORFs) were identified in each of the genomes, and differences between the two genomes were primarily observed in ORF 2. Only ORF 3 showed significant amino acid similarities to a putative rolling circle replication initiator protein (Rep), although with low identity (36%). Our phylogenetic analysis, based on the Rep protein, demonstrated that the CLV-BRs do not cluster with members of the Circoviridae, Nanoviridae or Geminiviridae families and are more closely related to circo-like genomes previously identified in reclaimed water and feces of a wild rodent and of a bat. The CLV-BRs are members of a putative new family of circular Rep-encoding ssDNA viruses. Electron microscopy revealed icosahedral (~23 nm) structures, likely reflecting the novel viruses, and rod-shaped viral particles (~65-460 × 21 × 10 nm in length, diameter, and axial canal, respectively). Circo-like viruses have been detected in stool samples from humans and other mammals (bats, rodents, chimpanzees and bovines), cerebrospinal fluid and sera from humans, as well as samples from many other sources, e.g., insects, meat and the environment. Further studies are needed to classify all novel circular DNA viruses and elucidate their hosts, pathogenicity and evolutionary history.