Using parenteral combination adjuvants to induce pan-mucosal cellular and humoral immunity

PROJECT SUMMARY Most pathogens enter the body at mucosal surfaces, yet, to date, the majority of licensed vaccines are injected parenterally, predominantly intramuscularly. While excellent at eliciting systemic immunity, they do not always induce the required mucosal immune responses. This highlights a gap in our understanding of how non-mucosal immunization might be manipulated to elicit mucosal immune responses and how such knowledge could be exploited to create better vaccines against mucosal pathogens. Defining the role that adjuvants play in this response is key to developing such vaccines; however, the mechanisms that dictate adjuvant driven mucosal antibody and cellular immune responses are not well understood. Our published work and preliminary experiments using major histocompatibility complex class I (MHCI) and II (MHCII) and B cell tetramers to examine mucosal immune responses after intradermal immunization with a novel detoxified bacterial ADP- ribosylating enterotoxin, called dmLT, demonstrate that we can retarget the endogenous T and B cell immune responses to the lung, intestinal mucosa, and female reproductive tract (FRT). When dmLT is combined with a safe, bacterial-derived outer membrane vesicle (OMV) adjuvant, CD4 T cell numbers and vaccine-specific antibodies and B cells are even further increased. Simultaneously, OMV adjuvant induces significant expansion of vaccine-specific CD8 T cells. Furthermore, immunization with dmLT- or OMV-adjuvanted vaccines elicits protection against bacterial infections in the lung and gut. These results lead us to hypothesize that intradermal immunization with combined dmLT plus OMVs will drive antigen-specific B cells and T cells to the mucosa and enhance vaccine protection against mucosal pathogens. We propose to: 1) determine how intradermal immunization with dmLT combined with OMV adjuvant directs 1) T cells and 2) B cells to mucosal tissue and whether these cells are bona fide tissue resident memory cells. In parallel, we will 3) examine if immunization with dmLT-OMV adjuvanted vaccines is protective against mucosal viral and bacterial infections in the lung, gut and FRT. This investigation will provide novel insights into how adjuvants regulate immunity at the mucosa and allow us to guide the response in favor of pathogen elimination.