HIV-1 RNA in Large and Small Plasmatic Extracellular Vesicles: a Novel Parameter for Monitoring Immune Activation and Virological Failure

Background: Antiretroviral therapy (ART) suppresses viral replication in most people living with HIV-1 (PLWH). However, PLWH remain at risk of viral rebound. HIV-1 infection modifies the content of extracellular vesicles (EVs). The changes in microRNA content in EVs are biomarkers of immune activation and viral replication in PLWH. Moreover, viral molecules are enclosed in EVs produced from infected cells. Our objective was to assess the value of EV-associated HIV-1 RNA as a biomarker of immune activation and viral replication in PLWH. Methods: Plasma samples were obtained from a cohort of 53 PLWH with a detectable viremia. Large and small EVs were respectively purified by plasma centrifugation at 17,000 x g and by precipitation with ExoQuick. HIV-1 RNA and microRNAs were quantified in the EV subtypes by RT-qPCR. Findings: HIV-1 RNA content was higher in large EVs of ART-naive PLWH. Small EVs HIV-1 RNA was equivalent in ART-naive and ART-treated PLWH and positively correlated with CD4/CD8 T cell ratio. In ART-naive PLWH, HIV-1 RNA content of large EVs correlated with small EV-associated miR-29a, miR-146a and miR-155, biomarkers of viral replication and immune activation. A receiver operating characteristics analysis showed that HIV-1 RNA in large EVs discriminated PLWH with a high CD8 T cell count. Interpretation: HIV-1 RNA in large EVs was associated with viral replication and immune activation biomarkers. Inversely, HIV-1 RNA in small EVs was related to immune restoration. Overall, these results suggest that HIV-1 RNA quantification in purified EVs could be a useful parameter to monitor HIV-1 infection.