Vaccination with the combination of Ag85B-TB10.4 and IC31® adjuvant generated a high amount of polyfunctional CD4+T cells expressing high levels of IFN-γ, TNF-α, and IL-2. This in turn led to significant protection against infection with M. tuberculosis in the mouse aerosol challenge model of tuberculosis. Both the immunogenicity of the vaccine and its ability to protect against TB infection was highly dependent on the antigen dose. Thus, whereas the standard antigen dose of 5 μg, as well as 15 μg, did not induce significant protection against M. tuberculosis, reducing the dose to 0.5 μg increased both the immunogenicity of the vaccine as well as its protective efficacy to a level comparable to that observed in BCG vaccinated mice. Thus, the IC31® adjuvant, with the specified antigen dose, can induce a strong protective Th1 response against M. tuberculosis.
