Multivalent Exosome based protein vaccine: a “mix and match” approach to epidemic viruses’ challenges

ABSTRACT Endemic viruses are becoming increasingly the norm, and the development of a rapid and effective vaccine is emergent. Here, we used our StealthX ™ exosome platform to express either Influenza H3 (Stealth™ X-Hemagglutinin, STX-H3) or SARS-CoV-2 Delta spike (Stealth™ X-Spike, STX-S) protein on the surface and facilitate their trafficking to the exosomes. When administered as single product, both STX-H3 and STX-S induced a strong immunization with the production of a potent humoral and cellular immune response in mice. Interestingly, these effects were obtained with administration of nanograms of protein and without adjuvant. Therefore, we tested the possibility of a multivalent vaccine: STX-H3 and STX-S exosomes were formulated together in a “mix and match” approach and the immune response was further evaluated. We showed that our STX-H3+S cocktail vaccine is as effective as the single components administered separately, resulting in a strong antibody and T-cell response. Our data show that our exosome platform has an enormous potential to revolutionize vaccinology by rapidly facilitating antigen presentation, and for therapeutics by enabling cell and tissue specific targeting.