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 on 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.