Heat-Shock Protein gp96 Enhances T Cell Responses and Protective Potential to Bacillus Calmette-Guérin Vaccine.

The commonly used Bacillus Calmette-Guérin (BCG) vaccine only induces moderate T cell responses and is less effective in protecting against pulmonary tuberculosis (TB) in adults and ageing populations. Thus, developing new TB vaccine candidates is an important strategy against the spread of Mycobacterium tuberculosis. Here, we demonstrated that immunization with heat-shock protein gp96 as an adjuvant led to a significantly increased CD4(+) and CD8(+) T cell response to a BCG vaccine. Secretion of the Th1-type cytokines was increased by splenocytes from gp96-immunized mice. In addition, adding gp96 as an adjuvant effectively improved the protection against intravenous challenge with Mycobacterium bovis BCG in mice. Our study reveals the novel property of gp96 in boosting the vaccine-specific T cell response and its potential use as an adjuvant for BCG vaccines against mycobacterial infection.