Fig. 1

Distribution of CpG islands in HBV genome. a The vertical axes indicate the GC percentage, and the horizontal axes represent the HBV nucleotide sequence. The blue areas refer to the CpG islands, while the vertical red lines under the horizontal axes represent CpG dinucleotides. The horizontal arrows represent the open reading frames of preS1/preS2/S, X, preC/C and p genes, while the vertical arrow indicates the split CGII. CGI, CGII and CGIII coexist in the first graph, while CGI is absent in the second graph, and CGIV is present in the third graph. b The frequency of strains containing CGIV in AHB, IT, CHB and ACLF group was compared by Chi Square test. CGIV was much more common in ACLF group compared to the other three groups (χ² = 59.76, P < 0.01)