Viruses Follow an Evolutionary Pathway

Abstract

Inherently, viruses are parasites that live inside cells. Viruses compete with their hosts to drive their own genomes and evolutionary paths, but they are evolutionarily autonomous despite their dependency on host cells. In at least two dimensions, viruses exhibit an immense diversity that surpasses that of their biological hosts. First, viruses efficiently use every information transmission scheme that is possible with the two types of nucleic acids. In contrast, cellular life forms use a consistent method of genetic information storage and expression with double- stranded (ds) DNA genome transcribed into various RNAs, including mRNAs that are translated into proteins. Secondly, virus gene sequences can span relatively larger parts of the sequence space because they usually evolve at a considerably faster rate than their biological homologs. It can be challenging to identify the deep evolutionary linkages and ancestry of virus genes because a single family of viruses might have sequence diversity greater than that of entire domains of cellular life. Identifying the deep evolutionary linkages and ancestry of virus genes can be extremely difficult. In this review, we will be highlighting the evolutionary history of viruses and their pathways alongside.