Tetrahydrothieno[2,3-c]pyridines as Vaccine Co-adjuvants

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Project Summary Vaccines consisting of antigen and adjuvant rely primarily on adjuvants for enhancement of immune stimuli. Despite the availability of FDA approved adjuvants, the need for co-adjuvants is evident since single adjuvant vaccines often do not generate long lasting protective immunity or immunity in immunocompromised and elderly population as evidenced by the thousands of deaths that occur every year despite the availability of influenza vaccines. A co-adjuvant is a substance that may or may not be an adjuvant by itself but can combine with a known adjuvant to offer synergistic effects such as enhanced antibody response. Our approach towards identifying novel co-adjuvants has focused on small molecules that may not lead to immune activation by themselves but enhance the primary immune activation such as nuclear factor kappa B (NF-κB) induced by a TLR-4 agonist. We developed novel high-throughput screening (HTS) approaches that led to identification of first-in-class compounds that prolong NF-κB activation when treated with Toll-like receptor-4 agonist LPS. The phenotypic assay used for HTS yielded several different classes of compounds with different mechanisms of action. One such chemotype tetrahydrothieno[2,3-c]pyridines showed most potent activity in our kinetic profiling screening and in vivo evaluation. Thus, we propose here to explore structure-activity relationship studies in the tetrahydrothieno[2,3-c]pyridine class of compounds with an aim to identify potent compounds and sites on the scaffold to introduce groups such aryl azide, biotin to obtain affinity/photoaffinity probes. These compounds will then be subjected to several in vitro assays for cytokine inductions in different cells to evaluate mechanisms of action and perform target identification using the affinity/photoaffinity probes. Finally, the potent compounds will be screened in vivo in mice for co-adjuvanticity with FDA approved adjuvant mono phosphoryl lipid A (MPLA) using model antigen ovalbumin to narrow down to two potent compounds which will be further screened in murine influenza vaccination to observe for survival post challenge with virulent dose of influenza virus, hemagglutinin inhibition and virus neutralization titers as well as virus titers in the lung.