Abstract
The significant number of people with latent and active tuberculosis infection requires further efforts to develop new vaccines or improve the Bacillus Calmette-Guérin (BCG), which is the only approved vaccine against this disease. In this study, we developed a recombinant fusion protein (PEPf) containing high-density immunodominant epitope sequences from Rv0125, Rv2467, and Rv2672 Mycobacterium tuberculosis (Mtb) proteases that proved immunogenic and used it to develop a recombinant BCG vaccine expressing the fusion protein. After challenging using Mtb, a specific immune response was recalled, resulting in a reduced lung bacterial load with similar protective capabilities to BCG. Thus BCG PEPf failed to increase the protection conferred by BCG. The PEPf was combined with Advax4 adjuvant and tested as a subunit vaccine using a prime-boost strategy. PEPf + Advax4 significantly improved protection after Mtb challenge, with a reduction in bacterial load in the lungs. Our results confirm that Mtb proteases can be used to develop vaccines against tuberculosis and that the use of the recombinant PEPf subunit protein following a prime-boost regimen is a promising strategy to improve BCG immunity.
Highlights
Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (Mtb) and is the leading cause of death by a single infectious agent worldwide
Given the demonstrated importance of proteases PepA, PepN, and Msh1 for the survival and virulence of Mtb, this work investigates the immunogenicity of a recombinant fusion protein composed of immunodominant epitopes from these proteases, development of a recombinant Bacillus Calmette-Guérin (BCG) vaccine and their use in different vaccination strategies for the prevention of TB in a murine model
Mycobacterium bovis BCG Moreau was cultivated in 7H11 agar supplemented with 10% Oleic Albumin Dextrose Catalase (OADC) and sodium pyruvate, and Middlebrook 7H9 medium with 10% OADC, sodium pyruvate, and 0.05% Tween 80 at 37 ◦C
Summary
Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (Mtb) and is the leading cause of death by a single infectious agent worldwide. PepA, a serine protease, was observed to stimulate the proliferation of peripheral blood mononuclear cells from tuberculin skintest-positive patients (latent TB individuals), indicating that Mtb expresses PepA during infection and is immunogenic [11] Due to these properties, PepA is one of the proteins included in the sequence of M72/AS01E, a TB vaccine tested in a clinical trial phase IIb. A follow-up 3-year study revealed that the vaccine’s efficacy for preventing pulmonary TB among latently infected individuals was 49.7%, with adverse events similar to those of the placebo control [12]. Given the demonstrated importance of proteases PepA, PepN, and Msh (besides their immunogenic capacity) for the survival and virulence of Mtb, this work investigates the immunogenicity of a recombinant fusion protein composed of immunodominant epitopes from these proteases, development of a recombinant BCG vaccine and their use in different vaccination strategies for the prevention of TB in a murine model
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