Induction of specific IgA responses in rats after oral vaccination with biodegradable microspheres containing a...

Diseases which affect mucosal surfaces cause considerable mortality and morbidity. New vaccine technologies are now available which justify a reappraisal of oral delivery not only for infectious disease control but also to control mucosal physiological processes such as fertility. Biodegradable microspheres have been investigated for their use as an oral delivery vehicle in rats using a recombinant antigen derived from fox sperm. Unencapsulated antigen administered in saline by the oral route produced a negligible response although an improved response was obtained if administered directly into the duodenum. This response was considerably enhanced if Peyer's patch (PP) priming was performed by direct injection of antigen in Freund's complete adjuvant (FCA) prior to intraduodenal (ID) delivery. In contrast, microencapsulated antigen given orally produced a substantial response, which was predominantly IgA specific, and almost equal in magnitude to that obtained by PP priming and ID boosting with native antigen. Direct ID delivery produced a similar response but when PP were primed with microencapsulated antigen in FCA the response to ID boosting was greater than with any of the other protocols investigated. These data demonstrate the efficacy of biodegradable microspheres in producing an IgA antibody response following oral vaccination.