Longitudinal bioluminescent imaging of HIV-1 infection during antiretroviral therapy and treatment interruption in humanized mice

Author summary Non-invasive bioluminescent imaging (NIBLI) in small animals allows for in vivo longitudinal imaging of infection spread and pathogenesis. We have taken advantage of the small luciferase reporter protein, Nanoluciferase (Nluc), to generate a replication-competent HIV-1 reporter virus to allow for NIBLI of viral infection in humanized mice. NIBLI via Nluc enabled us to directly visualize longitudinal spreading patterns before, during, and after interruption of daily doses of combined antiretroviral therapy (cART). We observed that rebounding infection often emerged in tissue regions originally associated with infected cells prior to cART treatment. Thus, Nluc-based NIBLI of HIV-1 infection can be used as an experimental tool to study events involved in viral dissemination and spread from initial sites of infection to draining lymphoid tissues before and after cART suppression, as well as locate infected tissues for subsequent cellular characterization of HIV-1 infected cells. Non-invasive bioluminescent imaging (NIBLI) of HIV-1 infection dynamics allows for real-time monitoring of viral spread and the localization of infected cell populations in living animals. In this report, we describe full-length replication-competent GFP and Nanoluciferase (Nluc) expressing HIV-1 reporter viruses from two clinical transmitted / founder (T/F) strains: TRJO.c and Q23.BG505. By infecting humanized mice with these HIV-1 T/F reporter viruses, we were able to directly monitor longitudinal viral spread at whole-animal resolution via NIBLI at a sensitivity of as few as 30-50 infected cells. Bioluminescent signal strongly correlated with HIV-1 infection and responded proportionally to virus suppression in vivo in animals treated daily with a combination antiretroviral therapy (cART) regimen. Longitudinal NIBLI following cART withdrawal visualized tissue-sites that harbored virus during infection recrudescence. Notably, we observed rebounding infection in the same lymphoid tissues where infection was first observed prior to ART treatment. Our work demonstrates the utility of our system for studying in vivo viral infection dynamics and identifying infected tissue regions for subsequent analyses.