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Title: HIV-1 transmission between T cells and macrophages : consequences for viral pathogenesis
Author: Baxter, Amy Elizabeth
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2013
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Within the paradigm of HIV-1 infection, macrophages play a crucial role as long-lived viral reservoirs. However, cell-free virus infection is inefficient and is unlikely to explain the levels of infection observed in vivo. To investigate the hypothesis that macrophages might be infected via direct contact with HIV-1-infected T cells, macrophage and HIV-1-infected T cell cocultures were imaged in real time. I observed that macrophages preferentially phagocytosed HIV-1-infected T cells and, using long-term culture assays, I established that following coculture the macrophage became productively infected. Phagocytosis of HIV-1-infected cells occurred independently of viral tropism; however, productive infection following T cell phagocytosis was restricted by viral tropism. Imaging flow cytometry showed that macrophages primarily phagocytose dying HIV-1-infected T cells. However, a significant population of HIV-1-infected 'healthy' cells were also taken up. Furthermore, ICAM-1 was identified as mediating the uptake of HIV-1-infected T cells. These results indicate that apoptosis plays a significant, but not sufficient, role in the mechanism for recognition and uptake of HIV-1-infected T cells. The response of macrophages to HIV-1 infection remains controversial. Using both primary macrophages and a monocyte/macrophage NFκB reporter line assay, I demonstrated that macrophages are activated in response to HIV-1-infected T cells. In addition, during coculture with HIV-1-infected T cells, macrophages upregulated secretion of Th1 cytokines, with associated dysregulation of regulatory cytokines. Finally, data presented suggest that polarisation of macrophages towards M1 and M2 phenotypes alters the susceptibility to HIV-1 infection in the cell-to-cell route.
Supervisor: Sattentau, Quentin J.; Moore, Rebecca A. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Infectious diseases ; Viruses ; macrophages ; CD4 T cells ; immune activation ; phagocytosis