Fig 3. Frequencies of relative synonymous codon usage for encoding the amino acids leucine and arginine.

RSCU for the different codons to encode the amino acids leucine and arginine, were calculated and compared between different groups of viruses and their respective hosts and for each virus and host. Each dot in the graphic represents a single virus or host. Different families of hosts and viruses were represented in different colors. In the case of leucine, Flaviviruses, alphaviruses and thogotoviruses displayed the same high predilection for the CTG codon as their natural hosts, using this codon as a first option to encode leucine, while in case of arginine, AGA was the codon with the highest RSCU among viral populations independently of their host preferences.