Quantitative Imaging Analysis of the Spatial Relationship between Antiretrovirals, Reverse Transcriptase Simian-Human Immunodeficiency Virus RNA, and Fibrosis in the Spleens of Nonhuman Primates

Although current antiretroviral therapy (ART) has increased life expectancy, a cure for human immunodeficiency virus (HIV) remains elusive due to the persistence of the virus in tissue reservoirs. In the present study, we sought to elucidate the relationship between antiretrovirals (ARVs) and viral expression in the spleen. We performed mass spectrometry imaging (MSI) of 6 different ARVs, RNAscope in situ hybridization of viral RNA, and immunohistochemistry of three different fibrosis markers in the spleens of 8 uninfected and 10 reverse transcriptase simian-human immunodeficiency virus (RT-SHIV)-infected rhesus macaques (infected for 6 weeks) that had been dosed for 10 days with combination ART. Using MATLAB, computational quantitative imaging analysis was performed to evaluate the spatial and pharmacological relationships between the 6 ARVs, viral RNA, and fibrotic deposition. In these spleens, .50% of the spleen tissue area was not covered by any detectable ARV response (any concentration above the limits of detection for individual ARVs). The median spatial ARV coverage across all tissues was driven by maraviroc followed by efavirenz. Yet.50% of RNA-positive cells were not exposed to any detectable ARV. Quantifiable maraviroc and efavirenz colocalization with RNA-positive cells was usually greater than the in vitro concentration inhibiting 50% replication (IC₅₀). Fibrosis markers covered more than 50% of the spleen tissue area and had negative relationships with cumulative ARV coverages. Our findings suggest that a heterogeneous ARV spatial distribution must be considered when evaluating viral persistence in lymphoid tissue reservoirs.