Tuberculosis Prevention: New TB Vaccine Shows Promise In Mice
Tuberculosis is still an epidemic that affects many countries across the globe. Now, a team of scientists is working on a new TB vaccine that has shown promise in mice. If it succeeds, it will be the first new TB vaccine in a century to battle drug-resistance.
With the rise of multidrug-resistant tuberculosis over the past years, treating the disease has become more difficult. A successful vaccine could benefit many people especially those living in low-and-middle-income countries, especially that the disease incurs a large annual death toll today.
The researches, who published the study in the Applied and Environmental Microbiology, a journal of the American Society for Microbiology, developed the vaccine that uses "biobeads" to place antigens from the tuberculosis bacterium into the body's own immune system. Biobeads, which are natural polyesters that non-tuberculosis bacteria, like Escherichia coli, assemble into tiny spheres.
The team has been able to engineer the biobeads to show antigens from tuberculosis bacteria, Mycobacterium tuberculosis or Mycobacterium bovis. In a previous study, the researchers found that mycobacterial antigens displayed on the biobeads could trigger a cell-mediated immune response in mice.
New TB Vaccine Shows Promise
The researchers observed that along with the tuberculosis antigens, E. coli proteins were attached to the surfaces of the biobeads.
"From these observations, we developed the hypothesis that these proteins could also function as antigens," Axel Heiser, Senior Scientist, AgResearch Ltd., said in a press release by the American Society for Microbiology.
"If produced in Mycobacteria instead of E. coli, such biobeads should carry mycobacterial antigens on their surface, including many as yet undiscovered antigens which would have the potential to induce protective immunity," he added.
However, unlike E.coli, Mycobacteria lack the enzymes needed to make biobeads. Hence, the team developed new cloning techniques that enabled expression of the enzymes in M. smegmatis, a type of mycobacterium that do not cause the infection. Using this bacteria would prevent the vaccine causing a TB infection.
When the researchers used the biobeads to vaccinate mice, they found cell-mediated immunity with the potential to be protected against TB. This new vaccine, if successful, could pave the way for protection against the potent pathogen.
At present, the vaccine available for TB, Bacille Calmette-Guérin (BCG), was created in 1921 and may cause infection in people with immunodeficiency. In 2015, about 10.4 million people contracted TB and 1.8 million people died across the globe. Nearly half a million of the new cases diagnosed were multi-drug resistant.