Induction of pulmonary immunity in cattle by oral administration of ovalbumin in alginate microspheres

Respiratory infectious diseases are an important cause of economic losses to the cattle industry. There is a need for an effective, easy to administer vaccine to the critical bacterial pathogens that cause pneumonia in cattle. An orally administered vaccine could be given to a large number of animals without significant stress to the animals and with minimal labor. The purpose of this study was to determine whether the oral administration of a model antigen (ovalbumin) in alginate microspheres could induce pulmonary immunity in cattle. Calves were vaccinated orally with ovalbumin (OVA) following either a subcutaneous (SC) or oral priming dose of OVA. Calves primed and boostered by oral administration (oral/oral) of OVA encapsulated in alginate microparticles had increased numbers of antigen-specific IgA ASCs (ASCs) in bronchoalveolar lavage (BAL) fluids. Calves that received a SC priming followed by an oral booster inoculation (SC/oral) of OVA in alginate microspheres had a greater number of anti-OVA IgA, IgG(1) and IgG(2) ASCs in BALF. SC/oral calves also had increased numbers of anti-OVA IgG(1) ASCs in peripheral blood whereas oral/oral calves had none. SC/oral calves had increased anti-OVA IgG(1), IgG(2), and IgA titers in BALF, and IgG(1) and IgG(2) in serum compared to both oral/oral and sham vaccinated calves. These results indicate that oral administration of antigen encapsulated in alginate microspheres results in a mucosal immune response in the respiratory tract of cattle. Furthermore, SC priming both enhanced the IgA response and stimulated an IgG(1) and IgG(2) response not seen in oral/oral calves. The difference in antibody isotype results suggest that design of the vaccination protocol can direct antibody responses as needed for a specific immunization program. (C) 1998 Elsevier Science B.V.