BLRD Research Career Scientist Award Application

Veterans Health Administration, Decatur PA

Investigators

Linked publications & trials

Abstract

The overarching goal of my research program is to understand tissue specific immunity with focus on the lungs. Immune cells continuously surveil the lungs to respond quickly to infections. Mycobacterium tuberculosis (Mtb) causes chronic tuberculosis (TB) and Francisella tularensis causes acute tularemia—two bacteria that cause respiratory infectious diseases. I have developed two large-scale T cell epitope discovery programs that leverage our strengths and my forte: the Merit supports the Mtb program; and AI137982 “Molecular Basis of CD1D and Natural Killer T Cell Function”, awarded in August 2019, after the RCS began, supports F. tularensis research. New support has been sought via a response to an RFA BAA-NIAID-DAIT-75N93022R00023: “FUNCTIONAL IMMUNOPEPTIDOMICS: Large-Scale F tularensis-derived Epitope Discovery & Correlates of T Cell Immunity”. Our Mtb work addresses a critical unmet need for an effective vaccine against TB that will significantly improve the quality of life of our Veterans. Mtb lives and multiplies within the host immune cell called macrophages, which are voracious eaters of bacteria and other foreign substances. Mtb has evolved ways to prevent macrophages from doing so, making life within infected cells possible. To get rid of the infection, the host needs to engage the killer cells of the immune system, one such killer cell is called CD8+ T cell. CD8+ T cells are equipped to find infected cells in very specific manner when antigens are presented in association with the hosts’ Human Leukocyte Antigen (HLA)-I molecule. HLA-I are different between individuals making T cell vaccine development difficult. Fortunately, HLA-I can be grouped into nine supertypes—B7 is one such supertype expressed by 40—45% of the human population. Once specific antigen recognition occurs, these effector cells deploy killing mechanisms to destroy the infected cells, leaving no place for the bacteria to live. Hence, the overarching goal of the Merit research is to develop a vaccine platform against TB that harnesses CD8+ T cell functions. This program leverages 30+ years of my experience in the field of antigen processing and presentation to T cells. Thus, in a systematic approach to vaccine design, our work involves pre-clinical studies that aims to identify MTb-derived antigens expressed only by infected macrophages so that CD8+ T cells can recognize such antigens, kill infected cells, and, thereby, confer protection to the host. In addition to vaccine design, our research will develop platforms for the delivery of next generation TB vaccines directly to the site of Mtb infection which is the lungs. We have made great strides toward both these goals: To facilitate the antigen discovery goal, we have developed new HLA-I transgenic humanized mouse lines. Then in a high-throughput antigen presentation assay that leverages a novel ultrahigh-density peptide arrays, we discovered 100s of peptide antigens that are presented by four common human MHC molecules. By bioinformatics approach we have winnowed down to 35 most likely MTb antigens recognized by CD8+ T cells, of which several are immunogenic Mtb-derived peptides and presented by members of the B7 supertype. Candidate antigens in these novel humanized mouse models are at the centre of the current investigations. Toward the development of platforms for vaccine delivery to the lungs—we have designed and validated nanoparticle platforms adjuvanted with three different chemicals that activate the innate immune system. The unique feature of these platforms is the ability to target the nanoparticle to the cytosol of a host immune cell called dendritic cell (DC), which are critical for antigen presentation to CD8+ T cells. We will harness this delivery platform to deliver the antigen/s discovered in the discovery phase of the project summarized above, tether the nanoparticle with an adjuvant to activate DCs, for delivery to the lungs. In summary, this pre-clinical, translational project is on an upward trajectory and will validate the ‘discover & deliver’ platform for a vaccine against TB. Success with this project brings with it the promise of delivering better health care to our Veterans, especially the downtrodden amongst them and, hence, the most burdened by the scourge of tuberculosis.