The purpose of this study is to evaluate the relationship between anti-retroviral therapy (ART) adherence with levels of human immunodeficiency virus (HIV) reservoir and residual viremia in suppressed, HIV-infected individuals on chronic ART.

Understanding whether the size and dynamics of the HIV reservoir are associated with adherence, measured by an objective biomarker, could have significant clinical and therapeutic implications for ART and HIV cure.

1. First, this aim will quantify levels of CA-RNA, CA-DNA, and plasma residual viremia in suppressed, HIV infected individuals and correlate them with levels of TFV-DP in DBS as a measure of cumulate drug exposure (adherence).
2. Second, this study will evaluate the changes in the HIV reservoir in relation to changes in ART adherence over time.

Inclusion Criteria:

1. HIV-infected males and females,
2. Ages 18 years and older,
3. Taking any TFV-based regimen,
4. HIV suppression <20 copies/ml for at least 12 months;
5. Not co-infected with HCV;
6. Able and willing to give informed consent.

Exclusion Criteria:

1. Pregnancy.
2. Refusal to participate.

HIV-infected individuals who are being treated with a tenofovir-based regimen.