RNA virus

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.

The International Committee on Taxonomy of Viruses (ICTV) classifies RNA viruses as those that belong to Group III, Group IV or Group V of the Baltimore classification system. This category excludes Group VI, viruses with RNA genetic material but which use DNA intermediates in their life cycle: these are called retroviruses, including HIV-1 and HIV-2 which cause AIDS.

As of May 2020, all known RNA viruses encoding an RNA-directed RNA polymerase are believed to form a monophyletic group, known as the realm Riboviria. The majority of such RNA viruses fall into the kingdom Orthornavirae and the rest have a positioning not yet defined. The realm does not contain all RNA viruses: Deltavirus, Asunviroidae, and Pospiviroidae are taxa of RNA viruses that were mistakenly included in 2019, but corrected in 2020.