Potential of polymer microencapsulation technology for vaccine innovation.

Biodegradable polymer microspheres or microcapsules developed over the past decade for reliable, preprogrammed release of contraceptive steroids have significant potential for adaptation to antigen release for immunization. In addition, polymeric encapsulation of antigens could prevent the acid and enzymatic degradation that has been a barrier to the development of oral vaccines. This review summarizes the published experience with microencapsulated hormones and antigens, describes the process of microsphere production, discusses the strengths and weaknesses of this approach to immunization, and outlines the gaps in knowledge. Microsphere technology has the potential benefits of reducing the number of inoculations, enhancing the immune response via both parenteral and oral vaccination routes, and in reducing the total antigen dose required to achieve immune protection.