Professional antigen presenting cells (pAPCs) process and present antigens on their cell surface in association with MHC class I molecules through two general pathways: direct or cross-presentation. The process of antigen presentation by pAPCs to naïve T cells resulting in their proliferation and differentiation into activated cytotoxic lymphocytes (CTLs) is called T cell priming. In these studies, we examine the cross-presentation of antigens from two non-replicating viruses: inactivated Lymphocytic Choriomeningitis virus (LCMV), and recombinant baculovirus encoding the LCMV nucleoprotein (NP). Since effective activation of pAPCs is essential for efficient priming of CD8+ T cells and CTL activation, and because infection with inactivated viruses generally induces an extremely poor level of CTL activation, we examined the activation state of pAPCs by measuring their cytokine profiles following infection to help further delineate their involvement in the CTL response to inactivated viruses. Our results indicate a pro-inflammatory cytokine mRNA upregulation in pAPCs in response to the inactivated virus, similar to the cytokine profiles subsequent to live LCMV infection, but to a lesser extent. In these studies, we also examined CTL activation following infection with inactivated LCMV and bAc-NP. We have demonstrated that the presentation of antigens from inactivated LCMV and bAC-NP results in a low level of CTL activation in vivo, though there is an undetectable level of CTL activation in vitro, in comparison to activation following infection with the live virus. Ultimately, the characterization of the cytokine profiles of pAPCs and the CD8+ T cell profiles induced in response to inactivated LCMV or the baculovirus derived NP may lead to a better understanding of how cross-presentation of these viral antigens may occur. This information may be applied to enhance the process of pAPC activation and T cell priming, for the induction of more effective cellular immune responses and the generation of stronger protective immunity. / Thesis (Master, Microbiology & Immunology) -- Queen's University, 2009-09-02 15:30:13.883

A dengue é uma arbovirose que ameaça mais de metade da população mundial. No momento existem duas vacinas, administradas por vias parenterais, aprovada ou em estudos clínicos, que podem conferir proteção parcial em regiões endêmicas, mas que ainda não estão sendo administradas em larga escala. Por outro lado, a utilização de vias de administração alternativas, como a via transcutânea (TC), pode ter um impacto importante na eficácia vacinal. A entrega de formulações vacinais pela via TC tem como vantagem a administração segura e não invasiva de antígenos vacinais e a composição celular específica da pele, rica em células apresentadoras de antígenos, como as células de Langerhans; O presente estudo demonstra que a via TC pode induzir respostas sorológicas vírus-específicas de forma eficiente quando utilizada para a administração de vacinas contra DENV baseadas em partículas virais. Portanto, novos estudos devem ser feitos considerando a TC como uma via de administração alternativa às vias parenterais para a administração de vacinas contra a dengue. / Dengue is an arbovirosis that threatens more than half the world\'s population. Currently there are two vaccines, both administered via parenteral routes, approved or in clinical trials, which provide partial protection but are not being administered on a large scale. On the other hand, the use of alternative routes of administration, such as the transcutaneous (TC) route, can have a significant impact on vaccine efficacy. Delivery of vaccine formulations via the TC route has the advantage of a safe and non-invasive administration method of vaccine antigens through the skin, that has a cell composition rich in antigen-presenting cells, such as the Langerhans cells. The present study demonstrates that the TC route can efficiently induce virus-specific serological responses when used for administration of DENV vaccines based on viral particles. Further studies should explore different dengue vaccines using the TC route as an alternative to parenteral administration routes.