Background:  HIV infection induces rapid lymphocyte turnover and the accelerated loss of telomere sequence that is believed to contribute to AIDS-associated immunosenescence. In this study we asked if HAART, by reducing HIV viral load and restoring T-cell counts, also arrested accelerated telomere erosion and if telomere length was restored in T cells repopulating the circulation.

Methods:  Blood samples from 16 HIV patients who had been characterized for telomere length in 1995 and subsequently treated with HAART, were collected and telomere lengths of peripheral blood mononuclear cells (PBMC) were determined and compared in parallel, pre- and post-HAART. Archived DNA samples from our previous study and PBMC of the same individuals 10 years after beginning HAART were purified, and telomere length was measured in the same gels by terminal restriction fragment (TRF) analysis.

Results:  Treatment with HAART blocked the accelerated telomere erosion normally seen in PBMC during HIV infection (p <0.0001). Patients on HAART showed an average loss of 65 bp/year compared with the ~52-bp/year loss seen in age-matched populations and the >180 bp/year seen upon HIV infection in the absence of HAART.

Conclusions:  HAART blocks the accelerated telomere erosion seen in the circulating component of the immune system during HIV infection. However, it does not restore telomere sequences previously lost, indicating that repopulation of PBMC from progenitor cells or activation of telomerase does not restore replication potential. Preservation of telomere length should be considered as a potential advantage favoring earlier HAART use.