Table 2. In vivo frequencies of mutations selected in vitro.

		HIV Subtype

Residue	Region	A	B	C	D

316T^a	V3	0.25 (13/53)^c	0.05 (27/528)	0.68 (318/469)	0.11 (7/61)
316A^b	V3	0.68 (36/53)	0.84 (443/528)	0.25 (119/469)	0.77 (47/61)

302K^a	V3	0 (0/53)	0.02 (9/528)	0.004 (2/469)	0.08 (5/61)
302N^b	V3	0.98 (52/53)	0.98 (521/528)	0.98 (461/469)	0.80 (49/61)

146I^a,d	V1	0.02 (1/53)	0.05 (28/528)	0.01 (4/469)	0.07 (4/61)
146T/S^b,d	V1	0.30 (16/53)	0.18 (94/528)	0.14 (66/469)	0.28 (17/61)

V1-Δ5^a	V1-V2	-^e	-	+	-
V1-no del	V1-V2	+^e	+	-	+

Mutant (a) and wild type (b) residues. (c) Frequency of mutant and wild type amino acid residues in HIV subtype-A (A1), -B, -C and −D sequences from the Los Alamos database; number of sequences over number examined in brackets. (d) As V1 is very difficult to align, numbers are approximations. (e) V1-V2 length comparison: regions with long loops were common (+) in subtypes −A, B, D, and rare (-) in subtype-C. In contrast, regions with shorter loops were common (+) in subtype-C and rare (-) in the other subtypes (the consensus subtype-C V1-V2 loop was 13 amino acid shorter than that of any other subtype)(www.hiv.lanl.gov).