A point mutation in the HIV-1 Tat responsive element is associated with postintegration latency

Area of Science:

• Virology
• Molecular Biology
• Immunology

Background:

• Understanding HIV-1 postintegration latency is crucial for developing effective treatments.
• The ACH2 cell line, a model for HIV-1 latency, exhibits impaired viral production upon Tat stimulation.
• The Tat protein and its responsive element (TAR) are key regulators of HIV-1 replication.

Purpose of the Study:

• To investigate the molecular mechanism underlying the Tat response defect in ACH2 cells.
• To identify specific mutations in the integrated HIV-1 genome that contribute to latency.
• To explore strategies for overcoming HIV-1 latency by targeting the Tat-TAR interaction.

Main Methods:

• Sequence analysis of tat cDNA and TAR regions in ACH2 cells.
• Functional assays including LTR transactivation and transient transfection.
• Introduction of specific mutations into an infectious HIV-1 clone and subsequent viral production analysis.
• Treatment of cells with tetradecanoyl phorbol acetate (TPA) or tumor necrosis factor-alpha (TNF-alpha).

Main Results:

• A point mutation (C37 -> T) was identified in the TAR region of integrated HIV-1 in ACH2 cells, impairing Tat responsiveness.
• This TAR mutation significantly reduced viral production, mimicking latency, which was partially restored by TPA or TNF-alpha treatment.
• A compensatory mutation (G28 -> A) in TAR restored wild-type Tat responsiveness, and introducing the C37 -> T mutation into an infectious clone resulted in TNF-alpha-dependent viral production.

Conclusions:

• A novel mutation in the Tat-TAR axis is identified as a significant factor contributing to HIV-1 latency.
• Alterations in the Tat-TAR interaction can be a critical determinant of the latent phenotype in HIV-1 infection.
• Targeting the Tat-TAR axis and understanding cellular cofactors like TNF-alpha may offer new therapeutic avenues for HIV-1 latency.