TABLE 1.

Genotypic profiles and resistance phenotypes of reconstructed protease inhibitor escape viruses^a

Virus	Protease inhibitor treatment	Mutation in HIV protease												Fold increase in IC90
		L10	K20	M36	M46	G48	F53	I54	L63	A71	V82	I84	L90
202post	Ritonavir		R	I					Pb		S			10
246post	Saquinavir				I	V			Pb				M	10
401post	Ritonavir		R	I				V			A			8.9
402post	Ritonavir	Ib	R	Ib	I		L		Pb	Vb	A			14.1
506post	Ritonavir		R						Pb		A		M	19

^aThe amino acid substitutions conferring HIV resistance to saquinavir and ritonavir are indicated in the single-letter code. The IC₉₀ was measured in a single-cycle resistance assay on P4 cells with the protease inhibitor included in the treatment as described in Materials and Methods. The results are expressed as the fold increase in the IC₉₀ compared to the value for a recombinant virus carrying the parental pretherapy protease. 

^bAlready present in pretherapy virus.