Abstract
Currently, there is only one licensed vaccine against tuberculosis (TB), the Bacillus Calmette–Guérin (BCG). Despite its protective efficacy against TB in children, BCG has failed to protect adults against pulmonary TB, lacks therapeutic value, and causes complications in immunocompromised individuals. Furthermore, it compromises the use of antigens present in the purified protein derivate of Mycobacterium tuberculosis in the diagnosis of TB. Many approaches, e.g., whole-cell organisms, subunit, and recombinant vaccines are currently being explored for safer and more efficacious TB vaccines than BCG. These approaches have been successful in developing a large number of vaccine candidates included in the TB vaccine pipeline and are at different stages of clinical trials in humans. This paper discusses current vaccination strategies, provides directions for the possible routes towards the development of new TB vaccines and highlights recent findings. The efforts for improved TB vaccines may lead to new licensed vaccines capable of replacing/supplementing BCG and conferring therapeutic value in patients with active/latent TB.
Highlights
Tuberculosis (TB), a disease caused by Mycobacterium tuberculosis (Mtb), is the leading cause of death due to an infectious agent in the world [1]
The World Health Organization has recommended the use of this test for diagnosing tuberculosis in low-resource settings [21], Bacillus Calmette–Guérin (BCG) vaccination compromises purified protein derivative (PPD)’s diagnostic value due to low specificity. This is because PPD is a crude mixture of several hundred proteins of M. tuberculosis and many of them are present in BCG as well, leading to antigenic cross-reactivity and causing a high rate of false positivity [22]
The study demonstrated that vaccination with MTBVAC, MTBVAC-L2, and MTBVAC-L3 had similar or superior protection compared to BCG in immunocompetent mice, when the immunized mice were challenged with the three representative strains
Summary
Tuberculosis (TB), a disease caused by Mycobacterium tuberculosis (Mtb), is the leading cause of death due to an infectious agent in the world [1]. The BCG vaccine protects children against TB for up to 10 years, but its efficacy declines with each subsequent year [7] It does not provide protection against adult pulmonary TB [8] and lacks any additional benefit upon revaccination of healthy and active TB cases [8]. The BCG vaccine was first produced in 1921, and because of its shortcomings, a more effective and safer vaccine is needed to replace or supplement it [9] Another worldwide epidemic, type 2 diabetes, is associated with a 2–4 times increased risk of developing active TB [10], and a known glucose control medication lowers the immune response to exacerbate the risk further [11]. This paper aims to give an overview of the TB vaccine candidates in the pipeline, discusses current vaccination strategies, and highlights recent findings
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