An adenovirus-based multiantigen vaccine protects against tuberculosis by coordinating adaptive immunity and curbing immunosuppressive mechanisms

Abstract

ABSTRACT Given that tuberculosis (TB) remains the leading cause of death from a single infectious agent, and that vaccination is the most effective control strategy, we systematically compared several vaccine construction strategies using a chimpanzee adenovirus vector platform. This led to the identification of a multi-antigen vaccine candidate, Ad-8 CP R2, as the most immunogenic construct. This candidate incorporates M. tuberculosis Ag85B, RpiB, and Rv2628 fused with the autophagy-inducing peptide C5 and Pan DR-binding epitope (PADRE) peptide. The C5 peptide in Ad-8 CP R2 vaccine enhanced the autophagic activity of antigen-presenting cells, thereby enhancing antigen presentation via the MHCI pathway and eliciting broad, multidimensional T-cell responses. Notably, Ad-8 CP R2 promoted the enrichment of tissue-resident memory T cells in the lungs, establishing local mucosal immunity that may restrict M. tuberculosis dissemination, while also generating antibodies capable of preventing M. tuberculosis infection. Furthermore, Ad-8 CP R2 limited the accumulation of myeloid-derived suppressor cells and alleviated T-cell exhaustion, thereby preserving adaptive immune function during chronic infection. Ultimately, we identified Th1 and Th17 responses, alongside functionally relevant antibodies, as key correlates of vaccine-induced protection. IMPORTANCE Current efforts in developing novel tuberculosis vaccines are to enhance the protective efficacy of vaccine candidates, with research primarily centered on rational vaccine design strategies for the generation of multivalent antigen constructs. In this context, we propose an approach involving the selection of M. tuberculosis antigenic proteins with strong immunogenicity and functional properties, which are then fused with peptide segments capable of augmenting antigen-specific immune responses. Delivery of these constructs via viral vector platforms induces robust and durable adaptive immunity. Such a strategy may further improve vaccine-mediated protection and could provide a theoretical foundation for developing next-generation tuberculosis vaccine candidates.