TABLE 1.

Proportions of synonymous and nonsynonymous nucleotide differences (P_s/P_n ratio^a) between different protease gene domains and PI critical sites

Subtype	Value for protease gene domainb
	AS	FR	PL	Rm	Totalc	PI CSd
B	22.2	11.4	17.4	3.2	6.5	6.8
F	21.3	10.5	14.4	3.5	6.3	6.7

^aThe average numbers of synonymous substitutions per potential synonymous site and potential nonsynonymous site relative to the Brazilian consensus B or F sequence were calculated for each domain and for nonsynonymous substitutions per the critical sites for mutations related to PI resistance. 

^bDomains: AS, active site (amino acid positions 21 to 34); FR, flap region (amino acid positions 42 to 56); PL, psi loop (amino acid positions 78 to 99); Rm, remaining regions for the molecule. 

^cThis value represents the P_s/P_n ratio with use of the whole protease gene of all samples for the calculations and comparison to the respective consensus sequence. 

^dThis value was calculated by using the critical sites at the following nucleotide positions: L10, K20, D30, V32, L33, M36, M46, I54, L63, A71, V77, V82, I84, N88, and 90L.