Genetically modified cold virus a 'promising' new TB vaccine

Researchers at McMaster University are heralding the early success of a “booster” vaccine that could serve as a potent tool in global fight against tuberculosis.

About 1.4 million people die each year from tuberculosis

Fiona Smaill, right, and Zhou Xing, both of the McMaster Immunology Research Centre, are leading a team of researchers in the testing of a new tuberculosis booster vaccine. (Supplied)

Researchers at McMaster University are heralding the success of early trials of a “booster” vaccine that could serve as a potent tool in global fight against tuberculosis.

In a report published on Wednesday in the journal Science Translational Medicine, researchers with the university’s Michael G. DeGroote School of Medicine detail a study they conducted with 24 human volunteers to test the safety of the vaccine.

Zhou Xing, a professor of pathology and molecular medicine at the McMaster Immunology Research Centre, said the test subjects developed no major side effects. Generally, their immune systems responded well to the vaccine.

“We are excited,” Xing said. “We are encouraged by these promising results.”

'We need new tools'

The vaccine, developed from a genetically modified version of the cold virus, is intended to function as a booster for the Bacillus Calmette-Guerin (BCG) vaccine, which was introduced the 1920s and is currently the only tuberculosis vaccine on the market.

According to Xing, the new vaccine helps reactivate immunity in people who have already been inoculated with the BCG vaccine.

The development of new vaccines is important, said Xing, because BCG  “is no longer effective enough to curb the global tuberculosis threat. So we need new tools.”

According to the World Health Organization, 8.7 million people fell ill with tuberculosis in 2011. In the same year, 1.4 million patients died from disease, a flu-like condition that attacks the lungs.

About one third of the world’s population is infected with the bacteria, with the highest rates of infection occurring in Asia and Africa. But a relatively small segment actually develops symptoms.

Infected people who also have HIV/AIDS are especially vulnerable to developing full-blown tuberculosis. 

The development also comes as scientists and health professionals gird for the continuing spread multidrug-resistant tuberculosis — strains of the bacteria that are immune to the most common antibiotics used to combat the disease.

The WHO estimates there were 310,000 cases of multidrug-resistant tuberculosis in 2011. Most occurred India, China and the Russian Federation. 

Multiple vaccines in development

The McMaster vaccine has been in the works for more than a decade. The team did clinical trials on animals first. It began its first clinical trials on humans in 2009 and finished last year. 

It’s critically important for us to push forward multiple vaccine candidates in order to determine which one will be the champion.—Zhou Xing, McMaster University

Despite Xing's enthusiasm about the recent report, he said it could be “quite a few years from now” that the vaccine is approved to go to market.

The McMaster team, Xing said, needs to do additional, much larger trials to test the vaccine’s effectiveness and safety.

According to the WHO, the vaccine is one of about 10 that are currently in the works worldwide.

“It’s critically important for us to push forward multiple vaccine candidates in order to determine which one will be the champion,” said Xing. 


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