Mucosal Immunity to Avian Influenza Following Ocular Immunization with Replication-Deficient Ad5-H5 in Chicken (41.15)

Abstract

Abstract Mucosal immunity plays an important role in the defense against viral pathogens. Limited information is available on the role of mucosal immunity in the chicken Harderian gland (HG) following ocular challenge. Although research has been performed on tears after ocular challenge or immunization of chickens, the mucosal immune response in the HG has not been well defined. To better understand mucosal immunity in HGs, we exposed chickens to a replication competent – free, recombinant adenovirus (Ad5) vaccine expressing the H5 gene of avian influenza (AI) virus. Expression of H5 in the HG after ocular administration of Ad5-H5 was demonstrated by immunohistochemistry. IgA and IgG H5- and Ad5-specific ELISPOT assays were developed to directly measure antibody-secreting B cells in HGs. The IgA and IgG spot-forming cells peaked on day 9 for Ad5 and day 11 for the H5 transgene. Ocular immunization induced Ad5- and H5-specific antibodies in the systemic compartment as measured by ELISA and HI assays, respectively. Increased levels of antibodies were also detected in tears. Western analyses demonstrated the presence of both monomeric and polymeric IgA in tears. RT-PCR analysis of HG derived mRNA confirmed the expression of the polymeric immunoglobulin receptor, confirming the importance of the HG as a mucosal effector site. Mucosal immunity was effectively induced by ocular application of the Ad5-expressed AI vaccine.