Table 4.

Susceptibility to Zidovudine and Stavudine of Participant-Derived Recombinant Viruses With or Without N348I

Mutations	Zidovudine			Stavudine
	IC50, Mean ± SD, µmol/L	Failure vs Pretherapya (P)	348I vs 348Nb (P)	IC50, Mean ± SD, µmol/L	Failure vs Pretherapya (P)	348I vs 348Nb (P)
Participant 1
Pretherapy	0.50 ± 0.21			10.0 ± 3.50
K103N/M184V	0.31 ± 0.21	0.62 (.24)	1.4 (.02)	4.25 ± 0.59	0.43 (.03)	1.5 (.16)
K103N/M184V/N348I	0.42 ± 0.26	0.84 (.93)		6.25 ± 1.53	0.63 (.22)
Participant 6
Pretherapy	0.47 ± 0.16			7.70 ± 1.30
Y181C/M184V	0.20 ± 0.04	0.43 (<.01)	1.8 (.04)	4.40 ± 1.22	0.57 (.10)	1.7 (.03)
Y181C/M184V/N348I	0.36 ± 0.06	0.77 (.17)		7.44 ± 1.14	0.97 (.68)
Participant 7
Pretherapy	0.25 ± 0.09			6.00 ± 1.30
V106A/M184V	0.22 ± 0.09	0.88 (.93)	2.2 (<.01)	5.02 ± 0.64	0.84 (.92)	1.2 (.07)
V106A/M184V/N348I	0.49 ± 0.21	1.96 (.04)		5.83 ± 0.69	0.97 (.11)
Participant 11
Pretherapy	0.39 ± 0.17			9.90 ± 1.70
K103N/Y181C/M184V	0.10 ± 0.04	0.26 (<.01)	2.2 (<.01)	4.69 ± 0.96	0.47 (.03)	1.0 (.81)
K103N/Y181C/M184V/N348I	0.22 ± 0.08	0.56 (.05)		4.44 ± 0.49	0.45 (.02)
Participant 12
Pretherapy	0.22 ± 0.03			5.70 ± 0.80
K103N/M184V/G190A	0.17 ± 0.07	0.77 (.26)	2.3 (<.01)	4.21 ± 0.27	0.74 (.14)	1.4 (.19)
K103N/M184V/G190A/N348I	0.40 ± 0.19	1.80 (.12)		5.87 ± 1.46	1.03 (.29)
Participant 13
Pretherapy	0.26 ± 0.08			5.10 ± 1.00
M184V/G190A	0.19 ± 0.03	0.73 (.37)	1.6 (.18)	4.92 ± 2.19	0.96 (.97)	0.94 (.92)
M184V/G190A/N348I	0.31 ± 0.19	1.19 (.71)		4.60 ± 1.36	0.90 (.92)

Abbreviations: IC₅₀, concentration required to inhibit viral replication by 50%; SD, standard deviation.

^a Mean fold change in IC₅₀ of recombinant virus with participant-derived reverse-transcriptase at virologic failure vs before therapy (pretherapy).

^b Mean fold change in IC₅₀ of recombinant virus with 348I vs 348N.