Vaccinating at Mucosal Surfaces with Nanoparticle-conjugated Antigen and Adjuvant

The incidence of tuberculosis (TB) has increased among Veterans in recent years because global TB burden has escalated with the emergence of multidrug-resistant and extremely drug resistant Mycobacterium tuberculosis (Mtb) strains. Further, current vaccines do not elicit long-lasting protective immunity against TB, especially in adults. Hence, this application addresses a critical unmet need for an effective vaccine against TB and thereby, significantly improve the quality of life of our Veterans. Herein, we propose pre-clinical studies that will identify protective CD8+ T cell epitopes and develop intranasal vaccine delivery platforms for the design of next generation TB vaccines. The global burden of TB caused by Mycobacterium tuberculosis (Mtb) infection is enormous. A third of the world's population is currently infected with Mtb, an airborne pathogen that causes ~1.5 million deaths annually. The escalating emergence of multidrug-resistant and extremely drug resistant Mtb strains for which treatment options are costly and limited, further exacerbates global burden. This problem persists because current vaccines do not elicit long-lasting protective immunity against TB, especially in adults. The challenge is multifaceted because Mtb enters the host through the respiratory tract and, therefore, optimal protection will require installation of lung-resident CD4+ and CD8+ memory T cells positioned at the frontline to respond immediately to an infection. Traditional vaccines and approved adjuvants typically elicit weak, short- lived T cell responses, and parenteral vaccination is ineffective at installing protective immunity within the mucosae. Moreover, most virus-vectored and subunit TB vaccines employ a small subset of Mtb antigens, resulting in insufficient epitope diversity for optimal protection, partly because the epitopes that are presented during Mtb infection and confer protective immunity are not fully defined. Hence, our overall objective is to discover immunogenic, protective Mtb epitopes and to incorporate them in an innovative nanoparticle (NP)- based intranasal vaccine designed to promote a balanced CD4+ and CD8+ T cell responses in the lungs that are protective against TB. As a means to accomplish this goal, we discovered >10,000 peptides that bind to HLA- A*02:01, B*07:02, B*35:01, & B*35:03 in a high-throughput binding assay using ultrahigh-density peptide arrays. Now the challenge is to identify epitopes recognised by Mtb-reactive CD8+ T cells that can protect against infection in a preclinical, humanised HLA-Itg mouse models. Moreover, using different infection models, we have developed multiple nanoparticle platforms for simultaneous delivery of antigens and adjuvants that efficiently generate protective, tissue resident CD8+ T cells (Trm). Guided by these exciting published and preliminary results, we will test this central hypothesis: Intranasal immunization with subunit vaccines consisting of novel Mtb antigens and adjuvant will generate CD8+ Trm responses in the lungs. Installation of Mtb-reactive CD8+ Trm at the port of pathogen entry will protect against a lethal, aerosol challenge of three novel humanised mouse models with [there] clinical isolate of virulent Mtb, [including] HN878. Our strategy to test this hypothesis is to, (a) define immunodominant CD8+ T cell epitopes presented by HLA-B*07:02 that protect B7.2tg mice from Mtb infections; and (b) define common immunodominant CD8+ T cell epitopes presented by multiple B*07:02-related alleles [called B7 supertype] that protect HLA-I transgenic mouse models from Mtb infections. Our multidisciplinary team -consisting of biochemists, immunologists, microbiologists, and bioengineer, is ideally situated to pursue the stated Specific Aims. We anticipate that successful completion of the proposed research will inform next generation vaccine design against Mtb infections and TB disease. Our innovative "discover and deliver" approach to vaccine design will impact clinical practice paradigms against TB and other pulmonary infectious diseases such as SARS-COVID19 and Flu. Thereby, vaccine paradigms emerging from our research bears with it the promise to significantly improve the quality of life of our Veterans.