Clinical measures of HIV provide insight into determinants of reservoir size / Erin H. Graf.

Graf, Erin H.
x, 147 p. : ill. ; 29 cm.
Local subjects:
Penn dissertations -- Cell and Molecular Biology. (search)
Cell and Molecular Biology -- Penn dissertations. (search)
Although current therapy regimens can suppress virus to levels that are undetectable by most clinical assays, there is still no cure for HIV. This is due to a stable pool of latently infected cells that cannot be targeted by antiretroviral therapy. Consequently, understanding the properties of this reservoir is vital to curing HIV. Existing in vitro latency models do not always reflect latency in vivo. Therefore this thesis presents both in vitro and in vivo experiments to examine reservoir levels as well as immune visibility of and potential therapeutic strategies to remove the reservoir. Specifically we examined the reservoir in a unique patient population called elite controllers, who control viremia without therapy, and compared it to that of treated and untreated non-controllers. This experimental paradigm enables us to probe the natural mechanism of reservoir control in controllers, which may be translated to new therapeutic avenues for all HIV infected individuals. By measuring HIV DNA intermediates in controllers, we found they contain very low levels of integrated HIV but relatively high levels of 2-LTR circles compared to non-controllers. This was not due to differences in cell susceptibility to virus. As integrated HIV DNA is far more efficient at expressing HIV proteins than unintegrated HIV DNA, we hypothesized the immune response may be preferentially clearing the former. Certain elite controller cohorts are known to have robust CD8+T cell responses to HIV, so we probed whether controller CD8+T cells could be responsible for low reservoir levels by targeting and clearing latently infected cells. We found CD8+T cells from controllers more efficiency cleared HIV protein-expressing resting cells using an in vitro coculture system, suggesting this is a mechanism of reservoir control in controllers. Furthermore, we found a correlation between reservoir size, as measured by our integration assay, and CTL clearance in our in vitro latent model. To test the in vivo relevance of these findings, we sorted HIV protein-expressing resting cells from HAART treated patients. The sorted cells were highly enriched for integrated HIV, suggesting that low level HIV protein expression is a feature of reservoir cells in HIV patients. In summary, these studies combined in vitro latency techniques with a unique patient population to identify a potential role for the immune system in controlling the HIV reservoir. These findings provide an important rationale for pursuing therapeutic vaccination to boost the immune response. As a portion of the reservoir may be visible without additional stimulation, vaccinations that boost CD8+T cell responses may be effective at clearing a portion of the HIV reservoir.
Adviser: Una O'Doherty.
Thesis (Ph.D. in Cell and Molecular Biology) -- University of Pennsylvania, 2013.
Includes bibliographical references.
O'Doherty, Una, advisor.
Hodinka, Richard L. committee member.
Betts, Michael R. committee member.
Collman, Ronald G. committee member.
University of Pennsylvania. Cell and Molecular Biology.
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