For years, scientists have been trying to come up with a better way to protect people from mycobacterium tuberculosis, a disease caused by Mycobacterium tuberculosis (Mtb) infection. Dr. Jordi Torrelles, a professor at the Texas Institute of Biomedical Research, said recent experiments in mice showed great hope. The study was published in the journal Mucosal Immunology.
“We found that our vaccine formula was better protected than the current vaccine and did not cause any lung tissue damage,” Dr. Torrelles said. “If further research proves safety and effectiveness, the vaccine can enter the lungs directly.” It is reported that the vaccine currently known as BCG is transmitted through intramuscular infection in the upper arm. “If it works, the human drug delivery system will spray through devices similar to asthma inhalers,” Dr. Torrelles explained.
According to the World Health Organization, tuberculosis caused by infectious organisms has become the world’s leading killer, so it is important to expand the number of people who can tolerate tuberculosis vaccines.
When bacteria enter the lungs, they come into contact with a lining called mucous membrane, which has enzymes that alter antigenic epitopes on the surface of microorganisms. Dr. Torrelles and his collaborators used biochemical methods to mimic the effect of lung lining fluids on the surface of bacterial cells so that more accurate vaccines could be made on a larger scale. The idea is based on that T cells (immune cells) will have a better memory response, identify bacteria and kill them.
Introduction to BCG vaccine
The current vaccine, BCG (Bacille Calmette-Guerin) is made from mycobacterium bovis, which is similar to Mtb in humans. Studies have shown that effective rate of BCG on the prevention of most serious tuberculosis such as tuberculous meningitis in children, is 70% to 80%. However, BCG is less effective in preventing respiratory diseases, which are the most common form of tuberculosis in adults. In addition, the immunity it provides to vaccinated people gradually weakens over time.
The BCG vaccine has not yet been used in the United States. According to the Centers for Disease Control and Prevention, the reasons are as follows: Americans have a relatively low risk of infection; BCG has no effect on adult tuberculosis; And the vaccine may interfere with tuberculin skin tests, making it more difficult to determine who carries the disease.
BCG cannot be given to immunocompromised people such as people living with HIV/AIDS. If these patients suffer from latent tuberculosis, they are ten times more likely to sicken for tuberculosis than those who do not have HIV/AIDS. Vaccines that can be given to this population have the potential to save millions of lives.
“Because Mtb infection occurs in the lungs, it makes sense to protect there,” Dr. Torrelles stressed.
Previous attempts of intranasal vaccination can lead to inflammation of the lungs and tissue damage. In Dr. Torrelles’s experiment with a new vaccine in mice, the inflammation rate of modified BCG was only 8 percent, while that of BCG was 20 percent (2.5 times less inflammation in the lungs). In addition, Dr. Torrelles predicts that the improved BCG vaccine will provide immunity at any age. This is particularly important for older persons at higher risk of tuberculosis. He said modifying the current vaccine would be an advantage because BCG has been approved by the Food and Drug Administration. Next, Dr. Torrelles hopes to secure funding to expand his research on non-human primates.