id	author	title	date	pages	extension	mime	words	sentences	flesch	summary	cache	txt
cord-353290-1wi1dhv6	Kustin, Talia	Biased mutation and selection in RNA viruses	2020-09-28		.txt	text/plain	7611	402	52	We investigated possible reasons for the advantage of A-rich sequences including weakened RNA secondary structures, codon usage bias, and selection for a particular amino-acid composition, and conclude that host immune pressures may have led to similar biases in coding sequence composition across very divergent RNA viruses. Nevertheless, RNA viruses do share several common features that drive their evolution: (a) their ultimate dependence on the cell, (b) their high mutation rates, (c) strong purifying selection derived from constraints operating on a small and densely coding genome, and (d) sporadic but powerful positive selection driven by an evolutionary arms race with the host they infect. Two non-mutually exclusive hypotheses may be put forth to explain the consistent pattern of A-richness that we observe: there is selection for more A in viral sequences, and/or there is a mutational bias that leads to more A in genomes of viruses.	./cache/cord-353290-1wi1dhv6.txt	./txt/cord-353290-1wi1dhv6.txt