Optimization and preclinical development of a TB Multiple Antigen Presenting System (MAPS) vaccine

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Project Summary/Abstract The overall objective of the proposed research is to optimize and further the development of a vaccine directed against Mycobacterium tuberculosis (Mtb) using a novel platform, the Multiple Antigen Presentation System (MAPS) developed by the Malley laboratory at Boston Children’s Hospital (BCH). Most current bacterial vaccines are based on enhancing the immunogenicity of polysaccharide (PS) capsular antigens (which determine serotype in many bacteria) by chemical conjugation to proteins. These vaccines suffer from limitations including an inability to elicit CD4+ Th1 or Th17 responses to antigens and high complexity of manufacture. For several organisms, T cell responses (either alone or in conjunction with antibody responses) are deemed necessary for mucosal or systemic protection. To overcome these limitations, we have developed MAPS, a vaccine platform that confers comprehensive immunity by eliciting antibodies to the PS and proteins, and CD4+ Th1 and Th17 responses to proteins. The technology is based on our discovery that proteins and PS linked via the affinity interaction between biotin and rhizavidin behave like a conjugate protein-PS vaccine, with the added benefit of generating robust CD4+ Th1 and Th17 responses to proteins. In preliminary studies, we have developed a TB MAPS vaccine composed of several Mtb proteins scaffolded onto a non-Mtb PS (pneumococcus type 1) which shows significant protection against pulmonary tuberculosis (TB) in a mouse model, particularly when combined with the live BCG vaccine; protection elicited by the combination of TB MAPS and BCG given concurrently at separate sites followed by 2 TB MAPS boosters is significantly greater compared to BCG or TB MAPS alone. Here, we will examine if protection by this TB MAPS construct can be augmented by the inclusion of one of three Mtb-specific PS. Our preliminary data strongly support the feasibility of this approach. To meet our goals, we have assembled a group of investigators that are experts in vaccine development (Dr. Malley from BCH and Dr. Pavliak from the International Vaccine Institute (IVI) in Korea, our industry partner) and tuberculosis research and animal models (Dr. Rubin from Harvard School of Public Health and Dr. Kaushal from Tulane University). The project will thus be a collaborative effort between investigators from academic institutions and a nonprofit agency with extensive experience in vaccine development (IVI). In the proposed experiments, we will evaluate whether the addition of Mtb PS to our current TB MAPS vaccine enhances protection in the mouse model, select the optimal TB MAPS vaccine (i.e. with or without Mtb PS, the proteins having been already selected) and then evaluate whether the combination of BCG given concurrently (at separate sites) with TB MAPS then followed by two booster doses of TB MAPS is superior to BCG alone in a nonhuman primate model of tuberculosis. A Product Development Plan has been prepared, which IVI will lead. These experiments, if successful, will pave the way for further development of this vaccine strategy for the prevention of TB.