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RNA viruses generally have very high mutation rates compared to DNA viruses, [8] because viral RNA polymerases lack the proofreading ability of DNA polymerases. [9] The genetic diversity of RNA viruses is one reason why it is difficult to make effective vaccines against them. [ 10 ]
Group VI: viruses possess single-stranded RNA viruses that replicate through a DNA intermediate. The retroviruses are included in this group, of which HIV is a member. Group VII: viruses possess double-stranded DNA genomes and replicate using reverse transcriptase.
This is in contrast to typical DNA-dependent RNA polymerases, which all organisms use to catalyze the transcription of RNA from a DNA template. RdRp is an essential protein encoded in the genomes of most RNA-containing viruses that lack a DNA stage, [ 1 ] [ 2 ] including SARS-CoV-2 .
Positive-strand RNA virus genomes usually contain relatively few genes, usually between three and ten, including an RNA-dependent RNA polymerase. [4] Coronaviruses have the largest known RNA genomes, between 27 and 32 kilobases in length, and likely possess replication proofreading mechanisms in the form of an exoribonuclease within nonstructural protein nsp14.
Viral evolution is a subfield of evolutionary biology and virology that is specifically concerned with the evolution of viruses. [1] [2] Viruses have short generation times, and many—in particular RNA viruses—have relatively high mutation rates (on the order of one point mutation or more per genome per round of replication).
The precise role of double-stranded (ds)RNA is still widely investigated as a central player in the Interferon System. Groups have found that positive-strand RNA viruses and dsRNA viruses produced significant amounts of dsRNA, but the precise methods mammalian cells leverage to distinguish between self vs. non-self dsRNA have yet to be uncovered.
The genes of viruses are made from DNA (deoxyribonucleic acid) and, in many viruses, RNA (ribonucleic acid). The biological information contained in an organism is encoded in its DNA or RNA. Most organisms use DNA, but many viruses have RNA as their genetic material. The DNA or RNA of viruses consists of either a single strand or a double helix ...
See also Comparison of computer viruses. This is an alphabetical list of biological virus families and subfamilies; it includes those families and subfamilies listed by the ICTV 2023 report. [1] For a list of individual species, see List of virus species. For a list of virus genera, see List of virus genera.