Tuberculosis kills two million people per year and so remains a very dangerous disease, though less so in America.

Researchers worldwide have been working to produce efficient tuberculosis vaccines but no one has created something that can ensure complete protection from the disease. The efficacy of one of the most widespread vaccines – BCG – varies from 80% to as little as 0%.

Specialists of the State Research Center for Virology and Biotechnology “Vector” have tested an experimental preparation for tuberculosis vaccinal prevention. The preparation is nontoxic and does not provoke an immune response in mice. Because it has not received all required verifications and approvals it cannot be called a vaccine yet.

The experimental 'vaccine' is a DNA fragment that codes the ESAT-6 mycobacterial antigen. Production of such a vaccine became possible after thorough investigation of genomes of mycobacteria – causative agent of tuberculosis – and of a congener bacterium - Mycobacterium bovis.

The majority of existing tuberculosis vaccines represent weakened mycobacteria cultures: a vaccine is supposed to provoke the immune response, but not the disease. The bacteria are weakened by removing from them the genes that are responsible for virulent properties, including the gene that codes the ESAT-6. It is absent from all existing Mycobacterium bovis BCG vaccine cultures. The Novosibirsk researchers staked specifically on this protein, which should not pose danger by itself .

Having established a proper genetically engineered construction, the researchers surrounded it by a polysacharide covering of polyglucin and spermidine. The covering reliably protects the DNA from enzymes that can destroy it. In the organism, polyglucin gradually decomposes, and the DNA becomes accessible to the immune system cells.

The mice were immunized by the obtained preparation for three times. The preparation was injected intramuscularly at a two-week interval. The reference group animals were immunized by polysaccharides and the DNA, which did not contain the vaccine gene.

After vaccination, the mice were observed for 10 more days, and during this period, they did not lose weight and did not show any other symptoms of health impairment. Nevertheless, the animals had to be slaughtered to investigate their immune system reaction. Vaccines should stimulate cell-mediated immunity, and indeed, lymphocyte clones were formed with mice after immunization.

The lymphocyte clones started to divide actively in response to introduction of the real ESAT-6 protein, at that the reaction significantly exceeded the background reaction. As for the reference group mice, their lymphocytes did not react to the protein injection.

The analysis has proved that specific cell-mediated immunity was formed with vaccinated mice.

This is not a vaccine yet but it is an important first step in its development.