HIV Antibody Increases Following Viral Rebound in People Receiving Antiretroviral Therapy

Inclusion Criteria: * HIV-positive individuals aged 15 or older at the time of ART initiation. * Participated in HIV plasma or serum biobanking and viral load testing, with three samples after January 1, 2015 as follows: * T1 specimen with suppressed VL and sufficient sample to conduct antibody testing. * T2 specimen collected 1-13 months after T1, with: Cases: unsuppressed VL; Controls: suppressed VL. * T3 specimen collected 1-13 months after T2, with sufficient sample to conduct antibody testing. * At least one VL measurement recorded prior to T1, with: * All VL measurements made in the year prior to T1 showing suppressed VL. * If no VL measurements were made in the year prior to T1, the most recent VL measurement made prior to T1 showing suppressed VL. Exclusion Criteria: * Individuals with advanced HIV disease from 1 year prior to T1 until T3, defined as: * CD4 cell count \<200 cells/mm3. * Any AIDS-defining illnesses. * Individuals with severe illness or hospitalization from 1 year prior to T1 until T3. * Individuals with immune disorder or cancer diagnosis from 1 year prior to T1 until T3. * Individuals with known recent infection at time of ART initiation (ART initiated within 1 year of estimated date of detectable infection). * Individuals known to have been infected with HIV perinatally.