Conjugation of antigens to the surface of BCG vaccine: application of the avidin-biotin system

Abstract

Schistosomiasis is a parasitic disease of severe morbidity caused by parasites of the genus Schistosoma. The disease affects millions of people around the world, especially in developing countries, including Brazil. To date, there is no preventive vaccine to combat the disease and, thus, the control of the disease has been based solely on praziquantel, a drug that although effective, does not prevent reinfections and can lead to the emergence of strains more resistant to treatment. It is believed that the development of a vaccine is possible because immunization with irradiated cercariae is capable of providing protection in different animal models. However, the antigens tested to date have induced partial protection. The hypothesis is that an improvement in formulations, the use of antigenic combinations or better vehicles of presentation can modulate the immune response against these antigens and provide protection in the face of the challenge. In our laboratories, an antigen presentation system based on biotinylated OMVs (outer membrane vesicles) and genetically fused antigens derived from avidin has demonstrated a great potential in activating the cells of the innate immune system and inducing a potent immune response in immunized mice. In this project, we propose the use of the BCG vaccine (Bacillus Calmette-Guérin) as a presenter of S. mansoni antigens, performing the conjugation of the antigens by binding avidin derivative in fusion with the antigens, to biotin molecules conjugated to the BCG surface. (AU)