Mycobacterium tuberculosis components expressed during chronic infection of the lung contribute to long-term control of pulmonary tuberculosis in mice

Abstract

Tuberculosis (TB) remains a major cause of mortality and morbidity worldwide, yet current control strategies, including the existing BCG vaccine, have had little impact on disease control. The tubercle bacillus modifies protein expression to adapt to chronic infection of the host, and this can potentially be exploited to develop novel therapeutics. We identified the gene encoding the first step of the Mycobacterium tuberculosis sulphur assimilation pathway, cysD, as highly induced during chronic infection in the mouse lung, suggesting therapies based on CysD could be used to target infection. Vaccination with the composite vaccine CysVac2, a fusion of CysD and the immunogenic Ag85B of M. tuberculosis, resulted in the generation of multifunctional CD4+ T cells (interferon (IFN)-γ+TNF+IL-2+IL-17+) in the lung both pre- and post-aerosol challenge with M. tuberculosis. CysVac2 conferred significant protection against pulmonary M. tuberculosis challenge and was particularly effective at controlling late-stage infection, a property not shared by BCG. CysVac2 delivered as a booster following BCG vaccination afforded greater protection against M. tuberculosis challenge than BCG alone. The antigenic components of CysVac2 were conserved amongst M. tuberculosis strains, and protective efficacy afforded by CysVac2 was observed across varying murine MHC haplotypes. Strikingly, administration of CysVac2 to mice previously infected with M. tuberculosis reduced bacterial load and immunopathology in the lung compared with BCG-vaccinated mice. These results indicate that CysVac2 warrants further investigation to assess its potential to control pulmonary TB in humans.

Delta inulin-based adjuvants promote the generation of polyfunctional CD4+ T cell responses and protection against Mycobacterium tuberculosis infection

“…CysVac2, a fusion protein comprising the M. tuberculosis Ag85B and CysD antigens, was previously found to provide protective immunity against pulmonary M. tuberculosis challenge in mice when formulated with MPL combined with dimethyldioctadecylammonium (DDA) 23 . Because of its high adjuvanticity, MPL is reported to be highly reactogenic 24 and does not adequately stimulate long-term T cell memory 25 .…”

“…Protein antigens Ag85B (Rv1886c), CysD (Rv1285), CysVac2 were produced in recombinant form from Eschericia coli as described previously 23 . Antigen purity was >90% as assessed by SDS PAGE analysis.…”

Mucosal delivery of a multistage subunit vaccine promotes development of lung-resident memory T cells and affords interleukin-17-dependant protection against pulmonary tuberculosis

“…To more precisely define the vaccine-specific responses after immunization with CysVac2/Advax, Ag85B:I-A b tetramer staining was employed to identify CD4 + T cells specific for the p25 epitope of Ag85B, an antigenic component of CysVac2 [17]. Ag85B tetramer-positive (Ag85Btet + ) cells in the lungs were only detected after i.t.…”

“…PBMCs were isolated from whole blood as previously described [17]. Single cell suspensions were prepared from the lung as previously described [17].…”

“…PBMCs were isolated from whole blood as previously described [17]. Single cell suspensions were prepared from the lung as previously described [17]. PE-conjugated Ag85B 240-254 :I-A b tetramer and APC-conjugated ESAT6 1-20 :I-A b tetramer were provided by the NIH Tetramer Core Facility.…”