Viral evolution

Viral evolution is change in the inherited traits of viral populations across generations, shaped by mutation, recombination, natural selection, and other processes.

Mutation: A change in genetic sequence that can create heritable variation. Mutations supply new variants on which selection and other evolutionary processes act.
Viral genome: The genetic material carried by a virus, made of DNA or RNA. Its sequence and organization define the heritable variation available to viral populations.
Molecular epidemiology: The study of genetic variation in pathogens to investigate their spread and population history. Viral sequence comparisons help reconstruct transmission patterns and track emerging lineages.
DNA virus: A virus whose genome is made of DNA. Many DNA viruses have lower mutation rates than RNA viruses because their replication machinery can proofread.
Natural selection: A process in which heritable traits affecting reproductive success change in frequency across generations. Variants that replicate or transmit more successfully can become more common in a viral population.
RNA-dependent RNA polymerase: An enzyme that copies RNA from an RNA template. Many viral versions lack proofreading, leading to frequent copying errors.
Phylogenetics: The study of evolutionary relationships using inherited characteristics, including genetic sequences. Viral phylogenies reveal ancestry, divergence, and the movement of lineages.
RNA virus: A virus whose genome is made of RNA. RNA viruses often generate substantial sequence variation during replication.
Genetic drift: Random changes in allele frequencies caused by chance sampling in finite populations. Chance bottlenecks can shift viral variant frequencies even when variants have no fitness advantage.
Viral replication: The process by which a virus makes copies of its genome and produces progeny particles. Replication creates generations in which mutations arise and variant frequencies change.

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