Antiviral activity of lamivudine in salvage therapy for multidrug-resistant HIV-1 infection.

Background: Maximum suppression of virus replication is often not achievable for persons infected with multidrug-resistant human immunodeficiency virus type 1 (HIV-1). Available data suggest that lamivudine contributes to partial viral suppression, despite the presence of M184V mutations and high-level phenotypic lamivudine resistance.

Methods: Selective lamivudine withdrawal was studied in 6 subjects who had incomplete viral suppression during antiretroviral treatment for multidrug-resistant HIV-1 infection.

Rate of thymidine analogue resistance mutation accumulation with zidovudine- or stavudine-based regimens.

Zidovudine (ZDV) and stavudine (d4T) select for the same set of thymidine analogue resistance mutations (TAMs). To compare the rate at which TAMs emerge, genotypic analysis of HIV-1 was performed on serial plasma samples from treatment-naive subjects randomly assigned to receive ZDV or d4T in combination with lamivudine. After 72 weeks of follow-up, TAMs were detected in samples from 50% of ZDV-treated subjects and 45% of d4T-treated subjects (P = 0.