TABLE 2.

Average numbers of nucleotide differences in pairwise comparisons of sequences within and between PERV classes

PERV class	PERV class of clones for comparison	No. of sequence comparisons	No. of differences (bp)
			Mean ± SD	Range
PERV-A	PERV-A	153	31.5 ± 11.53	5-54
	PERV-B	180	397.9 ± 4.50	388-408
	PERV-C	18	241 ± 6.76	222-254
	Recombinant PERV	90	144.5 ± 104.71	60-356
PERV-B	PERV-B	45	10.4 ± 5.62	1-24
	PERV-C	10	444.3 ± 2.41	440-448
	Recombinant PERV	50	283.9 ± 94.45	97-351
PERV-C	Recombinant PERV	5	301.0 ± 30.33	274-346