Hantavirus genomes are depleted for CpG dinucleotides and underlying evolutionary pressure is specific to CpG (not GpC) dinucleotides.

<p>(a) Among the 3 segments of hantaviruses the CpG dinucleotide O/E ratios for the M segment were significantly lower than that for the S segment (0.22±0.04 vs 0.28±0.06; P<0.0001) and that for the L segment (0.22±0.04 vs 0.29±0.05; P<0.0001). The differences in CpG O/E ratios of the S segment and the L segment were not significant (0.28±0.06 vs 0.29±0.05; P = 0.18). (b) The CpG/GpC O/E ratios were significantly lower for the M segment of hantaviruses as compared to those for the S segment (0.22±0.04 vs 0.29±0.07; P<0.0001) and for the L segment (0.22±0.04 vs 0.28±0.04; P<0.0001); clearly demonstrating that CpG dinucleotides but not GpC dinucleotides are susceptible to the underlying evolutionary pressures.