INDUCTION OF PULMONARY IMMUNITY IN CATTLE BY ORAL-ADMINISTRATION OF OVALBUMIN IN ALGINATE MICROSPHERES

Respiratory infectious diseases are an important cause of economic los ses to the cattle industry. There is a need for an effective, easy to administer vaccine to the critical bacterial pathogens that cause pneu monia in cattle. An orally administered vaccine could be given to a la rge number of animals without significant stress to the animals and wi th minimal labor. The purpose of this study was to determine whether t he oral administration of a model antigen (ovalbumin) in alginate micr ospheres could induce pulmonary immunity in cattle. Calves were vaccin ated orally with ovalbumin (OVA) following either a subcutaneous (SC) or oral priming dose of OVA. Calves primed and boostered by oral admin istration (oral/oral) of OVA encapsulated in alginate microparticles h ad increased numbers of antigen-specific IgA ASCs (ASCs) in bronchoalv eolar lavage (BAL) fluids. Calves that received a SC priming followed by an oral booster inoculation (SC/oral) of OVA in alginate microspher es had a greater number of anti-OVA IgA, IgG(1) and IgG(2) ASCs in BAL F. SC/oral calves also had increased numbers of anti-OVA IgG(1) ASCs i n peripheral blood whereas oral/oral calves had none. SC/oral calves h ad 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 enc apsulated in alginate microspheres results in a mucosal immune respons e in the respiratory tract of cattle. Furthermore, SC priming both enh anced the IgA response and stimulated an IgG(1) and IgG(2) response no t seen in oral/oral calves. The difference in antibody isotype results suggest that design of the vaccination protocol can direct antibody r esponses as needed for a specific immunization program. (C) 1998 Elsev ier Science B.V.