Thèse de doctorat : Pharmacie. Biologie, Médecine, Santé. Immunologie : Nantes : 2009. / Bibliogr.

Thesis (M. Phil.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 113-136). Also available in print.

Zugl.: Salzburg, Univ., Diss., 2005 / Hergestellt on demand

Thèse (M.Sc.)--Université Laval, 2009. / Bibliogr.: f. 73-81. Publié aussi en version électronique dans la Collection Mémoires et thèses électroniques.

Thesis (M.A.)--Queen's University at Kingston, 2001. / Includes bibliographical references.

Thesis (Ph. D.)--York University, 1999. Graduate Programme in Psychology. / Typescript. Includes bibliographical references (leaves 181-189). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNQ39307.

Thesis (Ph. D.)--University of Chicago, Committee on immunology, August 2003. / Includes bibliographical references. Also available on the Internet.

The causative agent of AIDS (acquired immune deficiency syndrome), HIV (human immunodeficiency virus), is one of the most extensively studied pathogens in modern history. The virus has multiple mechanisms of persisting in the host including evading host immune response. Since HIV-1 depends heavily on the host machinery for various aspects of its life cycle, unraveling the complex interplay between the host and HIV-1 could provide new clues to therapeutic avenues. In T cells, HIV assembles and subsequently buds through the plasma membrane incorporating host derived proteins and lipids in the viral envelope. HIV is thought to utilize a pre-existing mechanism for the budding of normal cellular vesicles called microvesicles to exit host cells. The evidence for this theory comes from reports of similarities between HIV and microvesicles observed for a small subset of proteins and lipids, leading to controversies about its validity. To further test this hypothesis, we utilized lectin microarrays to obtain a comprehensive glycomic profile of HIV and microvesicles derived from a panel of T cell lines. Glycosylation is critical to protein sorting and has a crucial role in HIV-1 biology, making it an ideal marker to compare the particles and the host cell membrane. We observed similar glycomic profiles for HIV-1 and microvesicles strongly suggesting an analogous mode of egress. Glycosylation of both particles seems to vary based on the parent cell line, providing additional evidence for this hypothesis. Microvesicles are involved in immune response modulation; hence the incorporation of microvesicular proteins could influence interactions of HIV with the immune system. The differences in glycosylation between these two particles could be potentially explained by the heavily glycosylated viral envelope glycoprotein. I also demonstrated that these vesicles bud from particular glycan enriched domains of the plasma membrane. Additionally, this work sheds light on the potential mode of interaction between galectin, an immune lectin and HIV-1. This work strongly argues for a conserved mechanism of exocytosis for both particles and sets the stage for examining the role of glycosylation in trafficking of proteins to the sites of microvesicular and viral budding. / text

Hydrogels, defined as three-dimensional, hydrophilic networks, offer extensive biomedical applications. The areas of application are heavily concentrated in drug delivery and tissue engineering because of the hydrogels’ ability to mimic extracellular matrixes of tissue while maintaining a high level of biocompatibility. Specifically, poly(ethylene glycol) (PEG) is a well-established biomaterial in hydrogel applications due to its high water-solubility, low toxicity, high biocompatibility, and stealth properties. This thesis discusses two applications of PEG-based degradable hydrogels. The first is the targeted, site-specific, controlled release of biologic drugs administered by inhalation. There are many challenges to designing a pulmonary delivery system for inhalation of biologic drugs such as low respirable fractions and short resident time in the lungs. In this report, the hydrogel microcarriers for encapsulated drugs were formed by cross-linked PEG and peptide sequences synthesized during a mild emulsion process. The microgels underwent freeze-drying in the presence of cryoprotectants and formulated for dry powder inhalation. The microgels displayed swelling properties to avoid local macrophage clearance in the lungs and exhibited triggered release and degradation in response to enzyme for disease specific release. Dry formulations were tested for aerosolization properties and indicated ability to be delivered to the deep lung by a dry powder inhaler. Lastly, microgels were successfully delivered to mice lungs via intratracheal aerosol delivery. This thesis also discusses the use of PEG-based hydrogel as a biomaterial microenvironment for encapsulated stem cells as a means of in vitro T cell differentiation. A 3D hydrogel system creates a biomimetic reconstruction of the cell’s natural microenvironment and allows us to adjust factors such as ligand density and mechanical properties of the hydrogel in order to promote cells differentiation. This report utilizes hydrogels of cross-linked hyaluronic acid and PEG to encapsulate mice bone marrow hematopoietic progenitor cells in the presence of notch ligands, displayed through stromal cells, magnetic microbeads, or immobilized within the hydrogel matrix. Mechanical properties of the hydrogels were tested and the release of encapsulated cells was performed by enzymatic degradation or dissolution. The differentiation data obtained indicated successful differentiation of stem cells into early T cells through the hydrogel system. / text

The outbreaks of human influenza caused by highly pathogenic avian influenza H5N1 virus have attracted a lot of attention and public concern. Effective and universal vaccines may be the best means for prevention and control of the influenza. Taking into account that viral clearance and recovery from influenza A virus infection have been demonstrated to be correlated to specific cytoxic T lymphocyte (CTL) instead of neutralizing antibodies, it is important to develop effective vaccines which are capable of inducing not only neutralizing antibody but also CTL responses. Furthermore, T cell epitopes are usually more conserved than neutralizing epitopes. However, rare information concerning human T cell epitopes specific to H5N1 virus has been reported so far. This study was designed to test our hypothesis that novel and potent human CTL and Th epitopes specific to NP protein of H5N1 virus may be identified in vaccinated and/or infected HLA-A2/DR1 transgenic mice (SURE/L1), while protective epitopes may be further defined from the identified T cell epitopes in the mice challenged with lethal dose of the virus. We used SURE/L1 mouse model because it contains HLA-A2 (*0201) and -DR1 (*0701), both are the second highest frequency of HLA class I and II in Chinese. Since the NP gene is relatively conserved among different clades or strains of H5N1 virus, we selected viral protein NP as the target. Furthermore, we screened the T cell epitopes in splenocytes not only from vaccinated mice but also from survived mice infected with gradually increased dose of H5N1 virus, because the T cell epitopes identified in both vaccinated and infected mice or in infected mice alone might have higher potential to be protective epitopes. In this study, a novel HLA-DR1 (class II) restricted T cell epitope NP368-382, NPII-7, was identified in both vaccinated and infected mice. Two doses of NPII-7 peptide boosting in the mice induced very strong Th1 and CTL responses but no NP specific antibody responses. The vaccination of additional 2 doses of NPII-7 also provided partial protection against lethal challenge of H5N1 virus in the mice, whereas NP DNA vaccination alone did not show any protective effect. The protective effect may be attributed to the strong Th1 and CTL responses induced by the NPII-7 vaccination, because both NP DNA and NPII-7 vaccinations could not induce neutralizing antibody response. Notably, a HLA class II restricted peptide, NPII-7, may induce not only Th1 responses but also more strong HLA class I restricted T cell (CTL) responses. It may probably due to that the HLA-DR1 restricted T cell epitope (NENMEAMDSNTLELR) contained the full sequence of a reported HLA-A2 restricted CTL epitope (AMDSNTLEL), named NP-17 in this study. Although it needs to be further defined whether this novel epitope is really a HLA-DR1 restricted T cell epitope, or it shares the activity of HLA-A2 restricted T cell epitope, or it is just an alternate HLA-A2 restricted T cell epitope, this study has identified a novel T cell epitope and proved that it is a protective T cell epitope. / published_or_final_version / Microbiology / Master / Master of Philosophy