Investigation of Macrophages Serving as a Viral Reservoir in Pediatric SAIDS

Abstract

Abstract In SIV-infected adult Macaca mulatta, increases in monocyte turnover indicates death of short-lived tissue macrophages and predicts SAIDS. Increased turnover also correlates with infection, not death, of long-lived tissue macrophages. Higher baseline monocyte turnover is measured in neonates, and faster disease progression. Our data shows increase in monocyte turnover and tissue macrophage infection is associated with rapid SAIDS progression in infants. We hypothesize early and high infection of macrophages results in establishment of viral reservoir in long-lived subsets, in infants not controlling viral load despite antiretroviral therapy (ART). In rhesus infants infected with SIVmac251, cell turnover is measured using BrdU uptake. Flow cytometry and confocal imaging allow phenotypic characterization of cells in blood and tissues. PCR and in situ hybridization are used to quantify SIV. Plasma cytokine analysis is performed using Milliplex bead panel. Infant macaques euthanized post-infection (no ART) are used to quantify macrophage infection. Animals euthanized after various lengths of ART provide data on reservoir seeding, viral persistence and immune activation status. ART-treated infants with discordant viral loads are evaluated to identify the source of viral replication. In treated animals, regardless of viral load, no differences are observed in activation status, absolute number, or kinetics of CD4 and CD8 T cells. Confocal imaging and viral RNA and DNA analysis of tissues and sorted cells should confirm that viral replication during ART is due to infected macrophages. Ongoing works suggest magnitude of long-lived macrophage infection may dictate effectiveness of ART in pediatric SIV infection.