HIV-1 Can Persist in Aged Memory CD4+ T Lymphocytes With Minimal Signs of Evolution After 8.3 Years of Effective Highly Active Antiretroviral Therapy

Background: Patients oil long-term highly active antiretroviral therapy (HAART) were studied to determine persistence, drug resistance development, and evolution of HIV-1 proviral DNA. Methods: Peripheral blood mononuclear cells were obtained by large volume blood drawn (500 mL) from 8 clinically successfully treated patients who had received uninterrupted HAART for up to 8.9 years. HIV-1 load was determined by Taqman real-time polymerase chain reaction. Drug resistance mutations were determined by sequencing and ultrasensitive, allele-specific, reverse transcriptase (RT)-polymerase chain reaction. Results: HIV-1 DNA load was significantly higher in aged memory (CD45RO(+) CD57(+)) when compared with memory (CD45RO(+) CD57(-)) and naive (CD27(+) CD45RO(-)) CD4(+) T cells after HAART. Sequencing revealed no major drug resistance Mutations in protease in all patients and appearance of resistance Mutations in RT in just 1 patient. In 1 of 5 patients with undetectable viremia during treatment, RT M184 substitutions were detected. Phylogenetic analysis showed short genetic distances between patient sequences. Conclusions: During long-term HAART, HIV-1 is able to persist in terminally differentiated CD4(+) T cells as proviral DNA. Viral evolution was restricted, and in 80% of the patients with undetectable viremia, no sign of viral replication could be detected.