Brucellosis, caused by Brucella, is one of the most common zoonosis. However, there is still no vaccine for human use. Although some live attenuated vaccines have been approved for animals, the protection effect is not ideal. In this study, we developed a dual-antigen nanoconjugate vaccine containing both polysaccharide and protein antigens against Brucella. First, the antigenic polysaccharide was covalently coupled to the outer membrane protein Omp19 using protein glycan coupling technology, and then it was successfully loaded on a nano-carrier through the SpyTag/SpyCatcher system. After confirming the efficient immune activation and safety performance of the dual-antigen nanoconjugate vaccine, the potent serum antibody response against the two antigens and remarkable protective effect in nonlethal
and lethal Brucella infection models were further demonstrated through different routes of administration. These results indicated that the dual-antigen nanoconjugate vaccine enhanced both T helper 1 cell (Th1) and Th2 immune responses and protected mice from Brucella infection. Furthermore, we found that this protective effect was maintained for at least 18 weeks. To our knowledge, this is the first Brucella
vaccine bearing diverse antigens, including a protein and polysaccharide, on a single nanoparticle. Thus, we also present an attractive technology for co-delivery of different types of antigens using a strategy applicable to other vaccines against infectious diseases.