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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).
A founder virus can introduce a different phenotype for the ensuing evolution. Evolution of viruses in nature and as disease agents can be viewed as succession of mutant spectrum alterations, subjected to expansions and reductions of population size in a continuous interplay of positive and negative selection and random drift.
New viruses and strains of viruses were discovered in every decade of the second half of the 20th century. These discoveries have continued in the 21st century as new viral diseases such as SARS [72] and nipah virus [73] have emerged. Despite scientists' achievements over the past one hundred years, viruses continue to pose new threats and ...
Levels of selection (evolution II) Vulnerabilities to disease can result when selection has opposing effects at different levels (e.g. genetic elements, cells, organisms, kin and other levels). Phylogeny (evolution II) Tracing phylogenetic relationships for species, populations, traits or pathogens can provide insights into health and disease.
New groups of viruses might have repeatedly emerged at all stages of the evolution of life. [16] There are three major theories about the origins of viruses: [16] [17] Regressive theory Viruses may have once been small cells that parasitised larger cells. Eventually, the genes they no longer needed for a parasitic way of life were lost.
The virulence of the virus may be changed, [5] or a virus could evolve to become adapted to a different host environment than that in which it is typically found. [5] Relatively few passages are necessary to produce a noticeable change in a virus; for instance, a virus can typically adapt to a new host within ten or so passages.
As fewer children die or are debilitated due to measles, mumps, rubella, diphtheria, tetanus and polio, we tend to forget that this is the result of an evidence-based childhood vaccination program.
Viral phylodynamics is the study of how epidemiological, immunological, and evolutionary processes act and potentially interact to shape viral phylogenies. [1] Since the term was coined in 2004, research on viral phylodynamics has focused on transmission dynamics in an effort to shed light on how these dynamics impact viral genetic variation.