Prevalence of drug resistant mutants and virological response to combination therapy in patients with primary HIV-1 infection.

Baseline genotype resistance analysis was carried out in 48 adults with primary HIV-1 infection between 1995 and 1998 before starting early combination therapy. Seventeen percent (8/48) of the isolates displayed key mutations conferring resistance to reverse transcriptase (RT) inhibitors such as amino acid substitutions 215Y/F (5/48,10%), 70R (3/48, 6%), 184V (2%). Two percent (1/48) had a major mutation associated with resistance to protease inhibitors (D30N). Other mutations at positions 10, 15, 20, 33, 36, 46, 63, 71, 77, 82, 93 of the protease gene were frequent (73%). Among the 46 patients who were given antiretroviral combination therapy and who responded durably to treatment after 6 and 12 months, there was no significant difference between those harboring RT mutant strains (Group I) and those with wild-type isolates (Group II). No significant difference was found at months 6 and 12 between the two groups in terms of CD4+ cell counts. These findings suggest that the presence of drug-resistant strains at the time of primary HIV-1 infection does not necessarily predict drug failure. Other factors, such as adherence to treatment, tolerance and pharmacokinetics parameters are probably major determinants of virological response in patients with early therapeutic intervention. Copyright 2000 Wiley-Liss, Inc.