Researchers funded by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, have developed an investigational aerosol tuberculosis (TB) vaccine that induced potent immune responses in a small number of rhesus macaques and protected them against pulmonary infection with Mycobacterium tuberculosis (Mtb). The findings appear in Nature Communications.
Currently, the Bacilli Calmette-Guérin (BCG) vaccine, first used in humans in 1921, is the only licensed vaccine available to help protect against TB infection in some people. However, it has considerable limitations: its protective effect in very young children wanes over time and it provides only limited protection against pulmonary TB, the most contagious form of the disease. In an effort to find a more effective alternative, NIAID-funded researchers at Tulane University developed an experimental aerosol vaccine with a modified form of Mtb bacteria that was genetically engineered to exclude a gene thought necessary for successful lung infection in macaques.
In their research, seven macaques were vaccinated with the aerosolized investigational Mtb vaccine and seven other macaques received an aerosolized version of the BCG vaccine. Another group of seven monkeys acted as the control arm. When given a lethal dose of TB eight weeks later, the scientists found that the investigational aerosol vaccine protected the animals from pulmonary TB infection better than the similarly delivered BCG vaccine.
Further, the researchers found that the experimental Mtb vaccine induced strong T-cell responses in the lungs of the vaccinated animals, which they theorize are key to protecting against pulmonary TB disease. Although further testing is needed, the results suggest that future TB vaccine candidates could be developed using the modified Mtb vaccine as a platform for a vaccine that provides more durable protection than BCG against TB disease, according to the authors.