Boosting with the subunit vaccine H65+ CAF01increased the BCG-protection against Mycobacterium bovis infection in a mouse model of bovine tuberculosis

GARCIA, ELIZABETH A.; AAGAARD, CLAUSS; BLANCO, FEDERICO C; BIGI, FABIANA

Simposio; Tuberculosis, Science Aimed at Ending the Epidemic; 2020

Bovine tuberculosis (bTB) is a lung disease caused by Mycobacterium bovis that mainly affects cattle. Although this disease is more prevalent in developing countries, in some developed countries like United Kingdom and New Zealand bTB is still a relevant issue for livestock. Bovine tuberculosis is not only detrimental to animal production, but also has a negative impact on public health as the bacilli can infect humans. To date, there are not vaccination programs against bTB, because of a number of issues that needs to be addressed. CAF01 has been used to formulate a subunit vaccine based on a fusion protein Ag85B-ESAT-6 or ESAT-6 that induced protection against M. tuberculosis challenge at levels comparable to the protective immunity induced by BCG vaccination in mice. The recombinant protein H65 is a fusion protein compound of EsxD, EsxC, ExsG, EsxH, ExsW and EsxV proteins. H65 formulated in CAF01 induced similar levels of protection in mice against M.tuberculosis challenge as BCG. Importantly, H65 lacks epitopes of ESAT-6 or CFP-10. Therefore, the use of H65 in combination with BCG is a bTB vaccine strategy compatible with a DIVA diagnostic test based on the most M. bovis antigenic proteins, ESAT-6 and CFP-10 .In this study, we assessed the protection conferred by H65 fusion protein formulated in CAF01 alone or in combination with BCG in a mouse model of bovine tuberculosis.