Researchers inch closer to the development of first new Tuberculosis vaccine in a Century

A new tuberculosis vaccine has shown promising results in trials on mice. If it succeeds , it is going to be the first tuberculosis vaccine in the century.

What is tuberculosis?

Tuberculosis is an infectious disease that affects lungs. It is caused by the bacterium Mycobacterium tuberculosis (TB). The mode of infection is through the air. It contacts when a patient suffering from TB  sneeze, during talking or even during cough.

Scenario of Tuberculosis

According to WHO (World Health organization), TB is one of the top 10 causes of death worldwide. WHO estimates in 2015, a number of 10.4 million people fell ill with TB and 1.8 million of them has died from the disease. More than 95% of TB deaths occur in low- and middle-income countries. Nearly 35% of HIV deaths are attributed to TB.

Challenges faced for the development of vaccine

Scientists are trying to  developa drug for TB since long, but no effective results are seen. It is estimated half of the people suffering from TB  has developed Multidrug resistance (MDR-TB). The MDR-TB gives a number of challenges because of which so far no effective drug has been made.

Research Methodology

In the new Research, vaccine uses bio beads to display antigens (a toxic or a foreign substance that incites an immune response in the body, especially the production of antibodies) of tuberculosis to the immune system. These bio beads are composed of natural polyesters assembled in non-tuberculosis bacteria. Researchers have engineered methods to display antigens from two strains of TB bacteria such as Mycobacterium tuberculosis or Mycobacterium bovis. In the research done earlier, researchers observed mycobacterial antigens displayed on bio beads induced the cell-mediated response in mice. The cell-mediated response is the type of immune response wherein, there is no involvement of antibodies but involves the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to the antigen. 

The bio beads are joined in E.coli bacteria so these beads contain mycobacterial antigens and also E.coli proteins on their surfaces. So this paved the way for the theory that these proteins may also act as antigens. So when the bio beads are produced mycobacterial strains, they must also contain mycobacterial proteins including many antigens that were unknown and this further increases the immune response to the vaccine. For this purpose, they chose M. smegmatis, a mycobacterium that does not cause tuberculosis. But mycobacteria do not contain enzymes to assemble bio beads. so they worked out cloning strategies that help in the expression of enzymes.

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Also unlike live vaccines (contain a particular form of the living microbe that has been made devoid of virulence in the lab, so it can't cause disease) using Non-tuberculosis bacteria prevents any chance of the vaccine that causes tuberculosis infection. After the preparation of bio beads, they opened the beads and found the beads to be natural and biodegradable. These bio beads, they injected into mice and tested for immune response. They observed the vaccine-induced cell mediated immunity that has the capacity to protect against TB. Future studies involve testing the vaccine in Mice followed by TB infection and devise methods for production and purification of the vaccine.

According to  Axel Heiser, Ph.D., Senior Scientist, AgResearch Ltd., Palmerston North, New Zealand, this new method is more safer cost efficient than the use of live vaccines and also evokes higher immune response due to a large number of antigens.

 The research is published January in Applied and Environmental Microbiology, a journal of the American Society for Microbiology.

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