Delivery of Vaccines by Biodegradable Polymeric Microcapsules with Bioadherence Properties

The objective of this program is to demonstrate the feasiility of using iodegradable polymeric microspheres for the encapsulation of vaccines which would produce effective protection for a minimum duration of one year with a single adminstration. Biodegradable microspheres made from poly (D-lactide co -glycolide) will be used. icrospheres will be prepared to provide release times that will correspond to the booster shot schedule of conventional immunization. The release kinetics of the microspheres will be chacterized in vitro, and the microspheres will be filled with the vaccine to be studied. In the Phase I program, botulinis toxoid vaccine and Clostridium will be tested in vivo to demonstrate the level of immunization produced, with the conventional immunization technique serving as an experimental control. These studies aare designed to demonstrate that the single dose microencapsulated vaccine produces an equivalent degree of protection. A single dose vaccine delivery system has the potential to signifi- cantly redce the cost and logistical complexity of providing routin immunizations for military personnel. Thjese same benefits are true for civilian use, where minimizing the need for patient compliance is a goal as well.