Development of oral microencapsulated forms for delivering viral vaccines

Rapid development in biotechnology during the last decade has allowed novel ideas in the development of antiviral vaccines to be considered and provides interesting technological approaches to their realization. Designing of microencapsulated forms for delivering bacterial and viral antigens or antigenic complexes using biodegradable biopolymers is an important novel direction. This approach involves the production of polymeric spherical particles with a diameter of 1 microm to 3 mm, containing isolated viral antigens or whole viral particles. Microencapsulated antigens administered orally are protected from low pH values of the gastric juice, bile acids, their salts and proteolytic enzymes of the gastrointestinal tract. The ability to drastically potentiate the immune response to encapsulated antigens, together with the ability to penetrate into the intestinal and respiratory mucosae upon oral and tracheal administrations, respectively, with induction of local and systemic immune reactions are the special merits of such polymers. However, the majority of data on microencapsulated viral vaccines has so far been obtained in animal models, as well as a limited number of studies on the protective effect they elicit. Certain success in the development of vaccines against a number of human viral infections, such as hepatitis B, cytomegalovirus and rotavirus, gives hope to successful completion of this research. Presumably, such vaccines will be safe and innocuous, simple in administration and capable of inducing both the systemic and local immune responses at the primary portal of viral infection.