• Graph: Tuberculosis figures

Tuberculosis is the communicable disease that causes more victims worldwide. Of the almost 10 million people who become infected each year, it is deadly for more than 1.5 million. There is a vaccine, Calmette-Guérin b acyl (BCG) , effective in preventing the most serious varieties in children, but not as effective in cases of pulmonary tuberculosis in adolescents and adults, the most common form of this pathology. In addition, the emergence of new antibiotic-resistant varieties adds additional pressure to find new ways of treating this disease.

A team of researchers from the University of Zaragoza has been working for decades on the development of the new vaccine ( MTBVAC ), with which they have obtained "hopeful" results in all clinical trials carried out so far. In one of them, carried out in 2015 in South Africa - where the disease is endemic -, this vaccine proved to be able to cause more robust and lasting immune responses than BCG, in similar doses. Details are published Tuesday in the online edition of The Lancet Respiratory Medicine.

Its creators point out that it is one of the most promising candidates to become the new global vaccine against the disease, since it is the only one derived from a live strain - although attenuated - of Mycobacterium tuberculosis (BCG comes from the Mycobacterium bovis , originated in cows). MTBVAC has been made from an isolated variety in a human patient who, through genetic engineering techniques, certain genes were eliminated to end his virulence. The researchers thus obtained a live, harmless bacterium, but capable of stimulating the immune system to stop the disease.

In addition, being more similar to the human pathogen, it has a much broader repertoire of antigens , substances capable of causing antibody release. "We think that our vaccine will better protect against the respiratory forms of the disease, because it contains more than 400 antigens absent in the BCG that are recognized by the immune system," explains Carlos Martín, principal coordinator of the Mycobacterial Genetic research group of the University of Zaragoza.

Long-term immunity

The first clinical trials with MTBVAC began in 2013 in Switzerland. Once its safety was confirmed, in September 2015, it was moved to a new stage (phase 1b) with the first tests in 36 newborns in South Africa to study the response to the antigens of the new vaccine in which it will be its target population . The results of this field work, which are published now, were analyzed for the first time in January last year and endorsed the step to phase 2, which has already been launched in South Africa. In this new stage it is sought to determine a balance point in its dosage, which protects from infection but keeps the side effects at minimum levels. "If the results are confirmed, we would like to move on to the last phase in 2020, in which the vaccine is already tested with populations of thousands of people," explains Martín, "just when 100 years have passed since the vaccine appeared. of the BCG ".

The objective of the Spanish researchers, in collaboration with the Galician biopharmaceutical Biofabri, is that MTBVAC be developed as a preventive vaccine for newborns, as well as a reinforcement for adolescents and adults previously inoculated with BCG at birth. "The next step is to demonstrate the effectiveness of MTBVAC," says Martín. "The sooner we can show its effectiveness in new trials, the sooner it can help us save millions of lives."

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