| Summary: | <p>HIV establishes a reservoir comprising long lived, latently infected CD4+ T cells and monocytic cells early during primary infection. This population represents a major barrier to an HIV cure. This thesis aimed to investigate the role of the immunological synapse in the failure of cytotoxic T lymphocytes (CTLs) to eliminate the HIV reservoir and the potential for engineered bispecific <b>I</b>mmune-<b>m</b>obilising <b>m</b>onoclonal <b>T</b> cell receptors <b>A</b>gainst <b>V</b>iruses (ImmTAV) to overcome this by redirecting fully functional CD8+ T cells against viral targets.</p> <p>A primary cell model of latency was used to investigate the expression of HIV Gag on latently infected cells and their susceptibility to ImmTAV-mediated elimination. A subset of cells expressed low levels of Gag without spreading infection and ImmTAV-redirected healthy donor CD8+ T cells were able to eliminate up to 40% of infected cells without latency reversal. CD8+ T cells from chronic HIV infected (CHI) donors showed impaired antiviral activity even with ImmTAV redirection.</p> <p>To investigate this further, confocal microscopy was used to study immunological synapse formation using primary CD8+ T cells from HIV-negative and CHI donors. CD8+ T cells from CHI donors were able to form conjugates with virus-infected cells but exhibited impaired synapse maturation, indicated by reduced Zap70 localisation, delayed microtubule-organising centre polarisation and impaired perforin recruitment to the synapse. ImmTAV redirection partially overcame these defects.</p> <p>Finally, the impact of antiretroviral agents on T cell mitochondrial function was explored. Exposure to zidovudine increased mitochondrial reactive oxygen species production and susceptibility to apoptosis. However, there was no evidence of impaired mitophagy.</p> <p>These data show that defects in CD4+/CD8+ T cell synapse maturation contribute to HIV persistence but nevertheless suggest that a subset of HIV reservoir cells may be susceptible to ImmTAV-mediated elimination. The therapeutic potential of ImmTAVs may depend in part on correction of CD8+ T cell exhaustion.</p>
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