Longitudinal trajectories of brain volume in combined antiretroviral therapy treated and untreated simian immunodeficiency virus-infected rhesus macaques

OBJECTIVES: We used simian immunodeficiency virus (SIV)-infected nonhuman primates to investigate longitudinal changes of brain volume caused by SIV and the effect of combined antiretroviral therapy (cART). In addition, the relation between viral load, immune status, and brain volume were explored. DESIGN: A longitudinal study of two healthy controls, five SIV(mac239)-infected macaques received cART (SIV+cART+) at 40 days postinnoculation, and five SIV(mac239)-infected macaques received no therapy (SIV+cART−). METHODS: Structural T1-weighted MRI, blood and cerebrospinal fluid testing were acquired at multiple time points for 48 weeks postinfection (wpi). Brain volume was estimated using region of interest (ROI)-based analysis. Volume differences were compared among three groups. Linear regression models tested the associations between brain volumes and biomarkers (viral load, CD4(+) T-cell count, CD4(+)/CD8(+) ratio). RESULTS: In our model, brain volume alteration in SIV-infected macaques can be detected at 12 wpi in several brain regions. As the infection progresses, the SIV+cART− macaques displayed generalized gray matter atrophy at the endpoint. Though initiate cART right after acute infection, SIV+cART+ macaques still displayed brain atrophy but showed signs of reversibility. Plasma viral load is mainly associated with subcortical nucleus volume whereas CD4(+) T-cell count and CD4(+)/CD8(+) ratio in plasma were associated with widespread cortical volume. CONCLUSION: The SIV(mac239)-infected Chinese origin macaque is a valid model for neuroHIV. Brain atrophy caused by SIV infection can be relieved, even reversed, by cART. Our model also provides new insights into understanding the pathogenesis of brain injury in people with HIV (PWH).