Fig. 1

Oligonucleotide frequencies in coronavirus genomes correlate with those of their host exon region. Venn diagrams of di-, tri-, and tetra-nucleotides that were specifically high in frequency in coronaviruses and host genomes. A Host exons, B Host introns, and C 100 kb fragments of human and bat genomes. In the comparison of oligonucleotide frequency between human- and bat-CoV, the oligonucleotide that was more frequent in human-CoV is denoted by CoV_H, and the oligonucleotide that was more frequent in bat-CoV is denoted by CoV_B. In the comparison of oligonucleotide frequency between human and bat exons, the oligonucleotide that was more frequent in human exons is denoted by Exon_H, and the oligonucleotide that was more frequent in bat exons is denoted by Exon_B. In the comparison of oligonucleotide frequency between human- and bat-introns, the oligonucleotide that was more frequent in human intron is denoted by Intron_H, and the oligonucleotide that was more frequent in bat intron is denoted by Intron_B. In the comparison of oligonucleotide frequency between 100 kb fragments of human and bat genomes, the oligonucleotide that was more frequent in the human genome is denoted by Host_H, and the oligonucleotide that was more frequent in the bat genome is denoted by Host_B