Detection of drug-resistant minority variants of HIV-1 during virologic failure of indinavir, lamivudine, and zidovudine.

We evaluated zidovudine-experienced patients for whom treatment with indinavir, lamivudine, and zidovudine failed, for indinavir-resistant minority variants. Of 10 patients with plasma human immunodeficiency virus type 1 RNA suppression and subsequent rebound, 6 without primary indinavir-resistance mutations underwent clonal analysis. One had evidence of V82A in 9 of 30 clones at week 24, with no increase at week 40. The dominant week-40 82V-M184V clones had changes at protease codons 62-64, compared with all clones at week 24 and minority clones at week 40. Resistance to indinavir can emerge during treatment failure in nucleoside-experienced patients but may be missed by routine sequence analysis. Selection for indinavir-resistant variants on treatment with indinavir, lamivudine, and zidovudine may occur slowly, depending on the genetic context in which they arise.