Fig. 6.

Selective loss of CpG motifs from a U-rich context in SARS-CoV-2 genomes to avoid immune recognition by TLR7: (a) The number of sequences that lost CpG motifs in an A/U-rich context was analyzed. The extent of CpG motif depletion from an A/U-rich context was comparable to that from the other CpG sites (i.e., non-A/U-rich context). (b) The selective loss of CpG motifs from SARS-CoV-2 genomes in a U-rich context (i.e., 4Us in the motif NNN-CG-NN) as compared with CpG motifs that are flanked by fewer Us (i.e., 1 to 3Us or no Us). There were no CpG motifs that were flanked by 5Us. Only CpGs outside ZAP-binding motifs (n = 352) were considered for this analysis (see Materials and Methods for details). The Mann–Whitney U test was used to compare the medians. TLR7, toll-like receptor 7.