An RNA virus is a virus—other than a retrovirus—that has ribonucleic acid (RNA) as its genetic material. The nucleic acid is usually single-stranded RNA (ssRNA) but it may be double-stranded (dsRNA). Notable human diseases caused by RNA viruses include the common cold, influenza, SARS, MERS, Covid-19, Dengue Virus, hepatitis C, hepatitis E, West Nile fever, Ebola virus disease, rabies, polio, mumps, and measles.
Podoviridae is a family of bacteriophage in the order Caudovirales often associated with T-7 like phages. There are 130 species in this family, assigned to 3 subfamilies and 52 genera. This family is characterized by having very short, noncontractile tails. Podoviradae are largely understudied and most new isolates are of the phicbkviruses genus, a group of giant viruses that appear to be Caulobacter specific.
Closteroviridae is a family of viruses. Plants serve as natural hosts. There are four genera and 59 species in this family, seven of which are unassigned to a genus. Diseases associated with this family include: yellowing and necrosis, particularly affecting the phloem.
Comovirinae is a subfamily of viruses in the order Picornavirales, in the family Secoviridae; its genera were formerly classified in the family Comoviridae. Plants serve as natural hosts. There are 62 species in this subfamily, assigned to 3 genera.
Fiersviridae is a family of positive-strand RNA viruses which infect prokaryotes. Bacteria serve as the natural host. They are small viruses with linear, positive-sense, single-stranded RNA genomes that encode four proteins. All phages of this family require bacterial pili to attach to and infect cells. The family has 185 genera, most discovered by metagenomics. In 2020, the family was renamed from Leviviridae to its current name.
Potyviridae is a family of positive-strand RNA viruses that encompasses more than 30% of known plant viruses, many of which are of great agricultural significance. The family has 12 genera and 235 species, three of which are unassigned to a genus.
Tymoviridae is a family of single-stranded positive sense RNA viruses in the order Tymovirales. Plants serve as natural hosts. There are 42 species in this family, assigned to three genera, with two species unassigned to a genus.
Rudiviridae is a family of viruses with linear double stranded DNA genomes that infect archaea. The viruses of this family are highly thermostable and can act as a template for site-selective and spatially controlled chemical modification. Furthermore, the two strands of the DNA are covalently linked at both ends of the genomes, which have long inverted terminal repeats. These inverted repeats are an adaptation to stabilize the genome in these extreme environments.
Lipothrixviridae is a family of viruses in the order Ligamenvirales. Thermophilic archaea in the phylum Thermoproteota serve as natural hosts. There are 11 species in this family, assigned to 4 genera. The genus
Globuloviridae is a family of hyperthermophilic archaeal viruses. Crenarchaea of the genera Pyrobaculum and Thermoproteus serve as natural hosts. There are four species in this family, assigned to a single genus, Alphaglobulovirus.
Alphaflexiviridae is a family of viruses in the order Tymovirales. Plants and fungi serve as natural hosts. There are 65 species in this family, assigned to six genera. Diseases associated with this family include: mosaic and ringspot symptoms.
Betaflexiviridae is a family of viruses in the order Tymovirales. Plants and fungi serve as natural hosts. There are 108 species in this family, assigned to 13 genera in two subfamilies. Diseases associated with this family include mosaic and ringspot symptoms.
Alphasatellites are a single-stranded DNA family of satellite viruses that depend on the presence of another virus to replicate their genomes. As such, they have minimal genomes with very low genomic redundancy. The genome is a single circular single strand DNA molecule. The first alphasatellites were described in 1999 and were associated with cotton leaf curl disease and Ageratum yellow vein disease. As begomoviruses are being characterised at the molecular level an increasing number of alphasatellites are being described.
Tristromaviridae is a family of viruses. Archaea of the genera Thermoproteus and Pyrobaculum serve as natural hosts. Tristromaviridae is the sole family in the order Primavirales. There are two genera and three species in the family.
Nyamiviridae is a family of negative-strand RNA viruses in the order Mononegavirales. Ecdysozoa and birds serve as natural hosts. The name is a portmanteau of Nyamanini Pan and Midway Atoll and the suffix -viridae used to denote a virus family. There are seven genera in this family.
Genomoviridae is a family of single stranded DNA viruses that mainly infect fungi. The genomes of this family are small. The genomes are circular single-stranded DNA and encode rolling-circle replication initiation proteins (Rep) and unique capsid proteins. In Rep-based phylogenies, genomoviruses form a sister clade to plant viruses of the family Geminiviridae. Ten genera are recognized in this family.
Smacoviridae is a family of single-stranded DNA viruses. The genomes of this family are small. The name Smacoviridae stands for 'small circular genome virus'. The genomes are circular single-stranded DNA and encode rolling-circle replication initiation proteins (Rep) and unique capsid proteins. As of 2021, 12 genera and 84 species are recognized in this family. The viruses in this taxon were isolated from faecal samples from insects and vertebrates by metagenomic methods. Little is known about their biology.
Botourmiaviridae is a family of positive-strand RNA viruses which infect plants and fungi. The family includes four genera: Ourmiavirus, Botoulivirus, Magoulivirus and Scleroulivirus. Members of genus Ourmiavirus infect plants and the other genera infect fungi. The member viruses have genomes which range from 2900 to 4800 nucleotides.
Solemoviridae is a family of non-enveloped, positive-strand RNA viruses which infect plants. Solemoviridae is a member of the order Sobelivirales.
Adnaviria is a realm of viruses that includes archaeal viruses that have a filamentous virion and a linear, double-stranded DNA genome. The genome exists in A-form (A-DNA) and encodes a dimeric major capsid protein (MCP) that contains the SIRV2 fold, a type of alpha-helix bundle containing four helices. The virion consists of the genome encased in capsid proteins to form a helical nucleoprotein complex. For some viruses, this helix is surrounded by a lipid membrane called an envelope. Some contain an additional protein layer between the nucleoprotein helix and the envelope. Complete virions are long and thin and may be flexible or a stiff like a rod.
