Simian Immunodeficiency Virus Targeting of CXCR3+ CD4+ T Cells in Secondary Lymphoid Organs Is Associated with Robust CXCL10 Expression in Monocyte/Macrophage Subsets

Glycosylation of Env defines pathogenic properties of simian immunodeficiency virus (SIV). We previously demonstrated that pathogenic SlVmac239 and a live-attenuated, quintuple deglycosylated Env mutant (Delta 5G) virus target CD4(+) T cells residing in different tissues during acute infection. SlVmac239 and A5G preferentially infected distinct CD4(+) T cells in secondary lymphoid organs (SLOs) and within the lamina propria of the small intestine, respectively (C. Sugimoto et al., J Virol 86: 9323-9336, 2012, https://doi.org/10.1128/JVI.00948-12). Here, we studied the host responses relevant to SIV targeting of CXCR3(+) CCR5(+) CD4(+) T cells in SLOs. Genome-wide transcriptome analyses revealed that Th1-polarized inflammatory responses, defined by expression of CXCR3 chemokines, were distinctly induced in the SlVmac239-infected animals. Consistent with robust expression of CXCL10, CXCR3(+) T cells were depleted from blood in the SlVmac239-infected animals. We also discovered that elevation of CXCL10 expression in blood and SLOs was secondary to the induction of CD14(+) CD16(+) monocytes and MAC387(+) macrophages, respectively. Since the significantly higher levels of SIV infection in SLOs occurred with a massive accumulation of infiltrated MAC387(+) macrophages, T cells, dendritic cells (DCs), and residential macrophages near high endothelial venules, the results highlight critical roles of innate/inflammatory responses in SlVmac239 infection. Restricted infection in SLOs by A5G also suggests that glycosylation of Env modulates innate/inflammatory responses elicited by cells of monocyte/macrophage/DC lineages. IMPORTANCE We previously demonstrated that a pathogenic SlVmac239 virus and a live-attenuated, deglycosylated mutant A5G virus infected distinct CD4(+) T cell subsets in SLOs and the small intestine, respectively (C. Sugimoto et al., J Virol 86:9323-9336, 2012, https://doi.org/10.1128/JVI,00948-12). Accordingly, infections with SlVmac239, but not with A5G, deplete CXCR3(+) CCR5(+) CD4(+) T (Th1) cells during the primary infection, thereby compromising the cellular immune response. Thus, we hypothesized that distinct host responses are elicited by the infections with two different viruses. We found that SlVmac239 induced distinctly higher levels of inflammatory Th1 responses than Delta 5G. In particular, SlVmac239 infection elicited robust expression of CXCL10, a chemokine for CXCR3(+) cells, in CD14(+) CD16(+) monocytes and MAC387(+) macrophages recently infiltrated in SLOs. In contrast, Delta 5G infection elicited only modest inflammatory responses. These results suggest that the glycosylation of Env modulates the inflammatory/Th1 responses through the monocyte/macrophage subsets and elicits marked differences in SIV infection and clinical outcomes.