| Most infectious agents cause disease either by colonization of or penetration of mucosal surfaces. Consequently, it becomes imperative to exploit methods which induce mucosal immune responses. In this collection of studies, we examined the effectiveness of a variety of well defined microbial products to enhance systemic and mucosal antibody responses to a coadministered test antigen. Moreover, we studied the effects of immunization route on the subsequent antibody responses. Native heat labile enterotoxin (LT) is shown to augment systemic and mucosal antibody responses when delivered via the nasal or ocular route. In addition, LT/vaccine (Escherichia coli beta galactosidase, beta-gal) admixtures strengthen antibody secreting cell (ASC) responses in the Hardarian gland, the point of immunization, over cohorts obtaining vaccine only. Ocular delivery of the B subunit of LT (LTB) with beta-gal was shown to be efficaous in the development of enhanced systemic IgA responses. Furthermore, LTB was shown to elicit greater numbers of ASC's within the splenic compartment of the immune system. Other microbial products utilized to alter the immune response during vaccination include lipopolysaccharide (LPS) and an attenuated LPS derivative termed Monophosphoryl lipid A (MPL). Lipopolysaccharide is shown to heighten systemic antibody responses when delivered via ocular and nasal routes in young chicks while adjuvant activity in older birds could only be obtained via ocular administration of LPS and vaccine. |
