Polyamides reveal a role for repression in latency within resting T cells of HIV-infected donors

Background. The persistence of human immunodeficiency virus (HIV) type 1 within resting CD4(+) T cells poses a daunting therapeutic challenge. Histone deacetylase (HDAC)-1, a chromatin-remodeling enzyme that can mediate gene silencing, is recruited to the HIV-1 long terminal repeat by the host transcription factor LSF. Pyrrole-imidazole polyamides, small molecules that target specific DNA sequences, can access the nucleus of cells and specifically block transcription-factor binding. Methods. We used polyamides to directly test the role of chromatin remodeling in HIV quiescence in primary resting CD4(+) T cells obtained from HIV-infected patients. Results. After exposure to any of 4 different polyamides that specifically block HDAC-1 recruitment by LSF to the HIV promoter, replication-competent HIV was recovered from cultures of resting CD4(+) T cells in 6 of 8 HIV-infected patients whose viremia had been suppressed by therapy. In comparison, HIV was not recovered after exposure to control, mismatched polyamides but was recovered from 7 of 8 of these patients' samples after the activation of T cells. Conclusions. We identify histone deacetylation as a mechanism that can dampen viral expression in infected, activated CD4(+) T cells and establish a persistent, quiescent reservoir of HIV infection.