McMaster University has created a vaccine that could serve as a powerful tool in the global fight against tuberculosis.
Researchers have developed a vaccine intended to function as a booster for the Bacillus Calmette-Guerin (BCG) vaccine, which was introduced in the 1920s and is currently the only tuberculosis vaccine on the market. The new vaccine would reactivate immune elements that over time diminish following BCG vaccination.
“TB is among what’s dubbed as the ‘big three’ infectious causes of death worldwide, which includes HIV, TB and malaria,” said Dr. Zhou Xing, a professor of pathology and molecular medicine at the McMaster Immunology Research Centre and one of the lead researchers. “The BCG vaccine is not effective enough to curb the TB epidemic. There is a need to continue (the) TB vaccine effort.”
More than a decade in the making, the vaccine was first tested on rodents and small animals. Over the past three years, it was given to 24 healthy volunteers from the community, including 12 who had previously received the BCG vaccine.
Results published earlier this month in the journal Science Translational Medicine showed the vaccine was safe and had a robust immune response.
Xing said the vaccine is a “genetically modified, harmless cold virus” that was developed to be used after BCG vaccination, which is given in most countries within the first year of life.
If successful, the university’s candidate vaccine may be given between the ages of three and five following BCG vaccination, he added.
“The genetical material it carries engages the immune cells in humans. We believe these ‘imprinted’ immune cells can help control TB,” Xing said. “Our published study is only the first important step. Quite a few more clinical studies are required before we know whether or not this vaccine can eventually make it into the human immunization program.”
TB is an infectious disease caused by various stains of mycobacteria.
It typically attacks the lungs and is spread through the air when people who have an active TB infection cough, sneeze or otherwise transmit respiratory fluids through the air.
Xing said if left undeterred or untreated, TB causes injury in the lung and the lung loses its function.
“An estimated one-third of the world’s population is latently infected by the bacterium that causes TB, but most of them never develop the disease,” he said. “When the immune system is weak, it may awaken and causes TB in about five to 10 per cent of these infected people. Every year, there are about eight to nine million new TB cases worldwide and 1.4 million die of this disease.”
Xing said McMaster’s vaccine has been more than 10 years in the making – from developing it and taking it through a series of testing in various animal models, including the mouse, guinea pig, goat and bovine models, to manufacturing the clinical grade vaccine.
“Dr. Fiona Smaill, an infectious disease specialist, and I began to prepare for this phase 1 clinical study in 2005; the study began in 2009 and was finished in 2012,” Xing said. “It has really been a long time coming, but both Fiona and I are proud of our progress as this vaccine carries a McMaster brandname and it has not been easy to get to where we are at today.”
Xing said he and Smaill are preparing for the next clinical study to be carried out at the university.
“This study will be larger than the one that we completed last year,” he said. “A major difference between the study under development and the last one is that the vaccine will be given directly into the lung in the next study. We have had an international TB vaccine organization on board to provide support, should our study get approved by Health Canada.”
Xing said developing such a vaccine is a “very arduous, but rewarding experience.”
“The McMaster vaccine is among 12 to 13 lead TB vaccine candidates in the world,” he said. “If all goes well, it may help control the TB epidemic.”
The development of the vaccine was supported by the Canadian Institutes of Health Research, the Canadian Foundation for Innovation, the World Health Organization, the Ontario Ministry of Research and Innovation, McMaster University and the Michael G. DeGroote Institute for Infectious Disease Research.