Probes for HIV-1

We describe a 53-year-old man with HIV-1 who received allogeneic CCR5Δ32/Δ32 hematopoietic stem cell transplantation (HSCT) in 2013 to treat acute myeloid leukemia. Four years after analytic treatment interruption (ATI), the absence of viral rebound and the lack of immunological correlates of HIV-1 antigen persistence provide convincing evidence for HIV-1 cure.

Despite decades of suppressive antiretroviral therapy (ART), HIV-1 reservoirs persist and fuel viral rebound if therapy is interrupted. The persistence of viral reservoirs in infected individuals is the main obstacle to achieving HIV-1 eradication or a long-term remission. Accurate assessment of the viral reservoir size is necessary for monitoring the effectiveness of the curative interventions. Here, we review the recent progress in the development of assays to measure HIV-1 persistence, highlighting their key advantages and limitations.To estimate the viral reservoir size, a number of assays have been developed that assess different aspects of HIV-1 persistence in ART-treated individuals. These include viral outgrowth assays to measure proviral replication competence, sequencing-based assays to measure genetic intactness of HIV-1 proviruses, and diverse techniques that measure the ability of proviruses to produce viral RNA and/or proteins (transcription and translation competence), with or without ex vivo stimulation. Recent years have seen the development of next-generation reservoir assays that, in addition to measuring viral persistence markers, assess the proviral integration sites and characterize the HIV-1 reservoir cells on the single-cell level.Although no assay yet can measure the HIV-1 reservoir with 100% accuracy, recent technical advances allow reliable estimation of its size and composition.

Defining the latent human immunodeficiency virus type 1 (HIV-1) burden in the human brain during progressive infection is limited by sample access. Human hematopoietic stem cells (hu-HSCs)-reconstituted humanized mice provide an opportunity for this study. The model mimics, in measure, HIV-1 pathophysiology, transmission, treatment, and elimination in an infected human host. However, to date, brain HIV-1 latency in hu-HSC mice during suppressive antiretroviral therapy (ART) was not studied. To address this need, hu-HSC mice were administered long acting (LA) ART 14 days after HIV-1 infection was established. Animals were maintained under suppressive ART for 3 months, at which time HIV-1 infection was detected at low levels in brain tissue by droplet digital polymerase chain reaction (ddPCR) test on DNA. Notably, adoptive transfer of cells acquired from the hu-HSC mouse brains and placed into naive hu-HSC mice demonstrated viral recovery. These proof-of-concept results demonstrate replication-competent HIV-1 reservoir can be established in hu-HSC mouse brains that persists during long-term ART treatment. Hu-HSC mice-based mouse viral outgrowth assay (hu-MVOA) serves as a sensitive tool to interrogate latent HIV-1 brain reservoirs.