Evaluation of Immune Responses and Protection in Mucosal Tissues Following Intranasal Immunization With a Recombinant Adenovirus Vector Expressing Glycoprotein B of Herpes Simplex Virus

Abstract

<p>In recent years there has been an increased interest in the design of vaccines capable of inducing immune responses in mucosal tissues and of providing protection against pathogens that invade through mucosal surfaces. Much of this interest has developed as a direct result of our greater understanding of the unique immune functions present in mucosal tissues. Numerous vaccine strategies have been developed to induce immunity in mucosaltissues and provide protection. The studies outlined in this thesis have utilized a recombinant adenovirus vector encoding the 0herpes simplex virus glycoprotein B (gB) gene (AdgB8) as a mucosal vaccine vehicle. The induction of gB-specific mucosal humoral and cellular immune responses was evaluated following intranasal and systemic routes of immunization. Immunological memory was also examined as was protection against mucosal infections with herpes simplex virus type-2 (HSV-2).</p> <p>Previous work has shown that adenovirus vectors expressing glycoprotein B of HSV-I are capable of inducing systemic antibodies and protection against systemic HSV infection. Evaluation of mucosal immune responses following intranasal AdgB8 immunization demonstrated IgG and IgA antibodies in mucosal secretions of the respiratory and genital tract. In contrast, systemic immunization only resulted in IgG antibodies in the genital tract. A thorough examination of antibody levels in the female genital tract revealed an isotype dependency on the stages ofthe estrous cycle. These observations become important when considering the maintenance of immunity throughout the estrous cycle.</p> <p>Currently, our understanding of the homing and recirculation patterns of memory lymphocytes suggests that immunological memory may depend on the tissues in which immune induction occurred. In addition, lymphocytes originating in mucosal tissues selectively migrate to local and distal mucosal tissues. To examine these phenomena functionally, CTL memory responses were evaluated in mice immunized with AdgB8. Functionally, short- and long-term CTL memory was found to depend on the route of immununization. These results are consistent with the recent literature and expand our current understanding of immunological memory on a functional level.</p> <p>Protection studies were then performed to examine the role of intranasal and systemic immunization in resistance to HSV-2 infections of the respiratory and genital tracts. From these studies it was clear that intranasal immunization provided optimal long-term protection. Taken together, the results presented here will have important implications in terms of developing successful mucosal vaccines designed to provide protection against sexually transmitted pathogens.</p>