Viral evolution

Viral evolution is a subfield of evolutionary biology and virology that is specifically concerned with the evolution of viruses. Many viruses, in particular RNA viruses, have short generation times and relatively high mutation rates (on the order of one point mutation or more per genome per round of replication for RNA viruses). This elevated mutation rate, when combined with natural selection, allows viruses to quickly adapt to changes in their host environment.

Viral evolution is an important aspect of the epidemiology of viral diseases such as influenza (influenza virus), AIDS (HIV), and hepatitis (e.g. HCV). The rapidity of viral mutation also causes problems in the development of successful vaccines and antiviral drugs, as resistant mutations often appear within weeks or months after the beginning of the treatment. One of the main theoretical models to study viral evolution is the quasispecies model, as the viral quasispecies.

Viruses are ancient. Studies at the molecular level have revealed relationships between viruses infecting organisms from each of the three domains of life and viral proteins that pre-date the divergence of life and thus the last universal common ancestor. This indicates that some viruses emerged early in the evolution of life, and that viruses have probably arisen multiple times.

There are three classical hypotheses on the origins of viruses:

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