Towards a more effective vaccine against tuberculosis

Of French and Italian researchers have developed an effective protection against the bacterium that causes tuberculosis in mice. Although results are preliminary, they raise the hope of tomorrow to have a more effective vaccine against the disease responsible for death of 1.5 million per year.

80% of TB patients live in sub-Saharan Africa. The limitations of BCG against pulmonary tuberculosis

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Tuberculosis is one of the most prevalent diseases in the world. It is due to infection by the mycobacterium Mycobacterium tuberculosis , affecting one third of world population. Each year, nearly 9 million people developed tuberculosis and nearly 1.5 million people die. About 80% of patients live in sub-Saharan Africa; it has not disappeared in France.

M. tuberculosis is thus one of the most virulent pathogens and most dangerous to humans. Facing him, BCG is effective in children but does not adequately protect adults against pulmonary tuberculosis, a highly contagious form. BCG (Bacilli Chalmette-Guerin) is prepared from an attenuated strain of bovine tubercle bacillus (Mycobacterium bovid). ” The first objective of the BCG vaccination is the prevention of severe forms of tuberculosis in infants and children, tuberculosis meningitis and military, with proven effectiveness of around 75%. (…) Immunization with BCG has a lesser effect (50% efficiency) over other forms of TB and does not affect the transmission of the tubercle bacillus “and stated the Ministry of Health during the plan against TB 2007-2009. In France, BCG is not mandatory but is recommended for children at high risk for tuberculosis.

Given the limitations of BCG, it appears necessary to develop a more effective vaccine to combat the disease. The hope for a more effective vaccine against tuberculosis.

Teams of researchers at the Pasteur Institute and Insert, in collaboration with a team from the University of Pisa, offering an innovative strategy of vaccination. They modified a portion of the genome of M. tuberculosis in order to obtain a non-virulent strain of this bacterium in mice. They blocked the production and transport of certain proteins called PE / PPE, revealing their essential role in the virulence of M. tuberculosis.

Injected in mice, this new mycobacterium “harmless” provides significant protection against development of tuberculosis. A specific immune response proteins (other than PE / EPE) still present in this strain. This mutant strain called Δppe25-PE19 could become a potential vaccine against tuberculosis, especially since it causes a stronger immune response than BCG in mice.

The discovery could lead to the development of a more effective vaccine than BCG, particularly against pulmonary tuberculosis in adults. However, other preliminary studies will be needed before tests on humans are considered, to ensure the effectiveness but also the safety of this strain inactivated. In this sense, the authors state that “the next step for researchers at the Pasteur Institute and Insert, will create a strain in which an additional mutation could be introduced in order to ensure total safety, to perform human trials. ”