TABLE 1.

Accumulation of mutations in gp90 of the env gene

Pony	% of envelope divergence from EIAVPV (mean ± SD)
	Nucleotide							Amino acid
	Disease cycle						Macrophage	Disease cycle						Macrophage
	I	II	III	IV	V	VI		I	II	III	IV	V	VI
561	0.03 ± 0.05	NAa	NA	NA	NA	NA	NA	0.11 ± 0.14	NA	NA	NA	NA	NA	NA
562	0.12 ± 0.04	NA	NA	NA	NA	NA	2.97 ± 0.014	0.28 ± 0.21	NA	NA	NA	NA	NA	8.14 ± 0.37
564	0.36 ± 0.26	0.57 ± 0.31	0.57 ± 0.22	0.76 ± 0.14	2.27 ± 1.4	1.92 ± 0.11	2.15 ± 0.11	0.41 ± 0.34	1.53 ± 0.61	1.54 ± 0.55	2.24 ± 0.34	7.86 ± 0.96	5.21 ± 0.15	5.08 ± 0.17
567	0.2 ± 0.10	0.41 ± 0.17	1.63 ± 0.17	1.55 ± 0.11	2.88 ± 0.10	3.04 ± 0.49	3.22 ± 0.51	0.41 ± 0.13	1.01 ± 0.38	5.12 ± 0.42	3.22 ± 0.35	7.46 ± 0.69	7.67 ± 2.97	7.44 ± 0.48

^aNA, not applicable.