Tuberculosis has been declared a global emergency by the WHO and a priority for vaccine development by the NIH. The currently used BCG vaccine offers variable protection against children but not adults. Various sub unit and DNA vaccines and attenuated mycobacterial vaccines are being evaluated as newer vaccines. We have developed an antigen 85A deficient attenuated candidate vaccine (?fbpA) from Mycobacterium tuberculosis that appears to be different from available vaccines in being highly immunogenic. Unlike wild type H37Rv and to a certain extent BCG, ?fbpA is not suppressive for macrophages or dendritic cells and enhances antigen presentation. Studies show that ?fbpA vaccine is more effective than BCG in the mouse vaccine evaluation model, primes T cells more effectively than BCG and induces a stronger T- bet dependent Th1 response in mice leading to a better protection. ?fbpA vaccine alone has the full complement of immunodominant antigens, Ag85B/ESAT-6/CFP-10/TB10.4 and phoP in a live attenuated vehicle. We propose that ?fbpA candidate vaccine will deliver these antigens in a highly immunogenic form and protect better against tuberculosis.
The Specific Aims are to 1) Develop a safer vaccine candidate using ?fbpA through genetic manipulations and, 2) Investigate the mechanisms of heightened immunogenicity of ?fbpA and protection against virulent M tuberculosis using animal models under the following sub aims. We will a) Characterize the immune responses in mice immunized with BCG and ?fbpA in an effort to more clearly define protective immune responses, b) Characterize the duration of the responses in mice immunized with BCG and ?fbpA in an effort to determine why BCG protection wanes, c) Investigate the ability of ?fbpA to boost the response to BCG, and d) Investigate the production of long term immune memory in??fbpA vaccinated mice. Finally, we will investigate the molecular mechanisms of enhancement of antigen processing by ?fbpA. The twin goals of this project are develop the safest possible vaccine for tuberculosis with enhanced immunogenicity and to characterize factors that enhance the immunogenicity of live mycobacterial vaccines.
This is a research grant proposal that seeks to develop a new vaccine for tuberculosis using genetic manipulations on the wild type Mycobacterium tuberculosis. Tuberculosis the leading cause of death due to bacterial infections and prevention of this disease through a vaccine will have an impact on the public health and future of mankind. AIDS and tuberculosis is a deadly combination in sub Saharan Africa and Asia and efforts are also needed to develop polyvalent vaccines. This proposal addresses this issue as well. We have developed a highly immunogenic vaccine that can be eventually used as a polyvalent carrier vaccine and in a safer form for multiple manifestations of the human disease. The project is a collaborative proposal which involves investigators at the University of Heath Sciences Center Houston (Drs. Jagannath, Hunter and Armitige) and Smith Research Center in Immunology, MD Anderson Cancer Center, Texas (Dr. Schluns) where advanced research in immunological memory are carried out. Dr. Hildebrand, Professor at University of Oklahoma and an expert in CD8 epitope mapping will also serve as a consultant.
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