Differences in G + C content and CpG and UpA representation in gene sequences of RNA viruses infecting mammals and birds. Comparison of virus composition between viruses infecting mammals and birds, expressed as fractional differences in G + C content and CpG and UpA dinucleotide representation calculated as f(M)–f(A)/f(All), where f(M) is the mean composition of mammalian viruses, f(A) is of avian viruses, and f(All) is the overall mean. Analyses were performed separately for (A) different virus families and (B) for different segments of flu strains isolated from mammalian (human) and avian sources (duck, chicken). Further analyses of differences between duck and chicken hosts, analyses where recently zoonotic H5N1 strains have been excluded and CpG and UpA representations calculated independently of protein coding are provided in Supplemental Data Table S15. Source sequences are listed in Supplemental Data Tables S10, S11.
