New hopes for highly effective TB jab

Scientists say they have developed a vaccine for tuberculosis that can completely eliminate tuberculosis (TB) bacteria and build up unprecedented protection in mice.


The only long used and available TB vaccine called BCG has found to be not so much effective in making protection with efficacy varying between 0 to 80 percent in different parts of the world.

The World Health Organization (WHO), however, says one in three people around the world is infected with Mycobacterium tuberculosis and about 1.7 million are killed by the disease each year.

Researchers at Albert Einstein College of Medicine in New York have developed a new highly effective prototype vaccine that managed to completely eliminate TB bacteria in some cases during a mice study.

To develop the new jab, scientists targeted a cluster of genes called esx-3, variants of which are in all types of Mycobacterium and help the organisms evade the immune system.

As Mycobacterium tuberculosis cannot survive without esx-3 genes the research team focused on its relative Mycobacterium smegmatis that is lethal to mice at high doses but cannot infect humans.
They deleted the genes from M. smegmatis and injected deadly doses of the microbe into mice. Within three days the mice had cleared the bacteria from the lungs and kidneys.

For the next step, the researchers replaced esx-3 genes of the M. smegmatis with those from Mycobacterium tuberculosis and injected high doses of the manipulated microbes to the studied mice.
Findings showed that modified microbes not only managed to cause infection but led to a strong and lasting immunity against M. tuberculosis.

According to the results published in the journal Nature medicine, mice vaccinated with BCG survived almost 65 days after being infected with TB while those immunized with the new jab survived on average for 135 days.

Those which received no vaccine died just 54 days after being infected with TB.

"Most notably, those vaccinated animals that survived for more than 200 days had livers that were completely clear of TB bacteria, and nobody has ever seen that before,” said senior researcher Professor William Jacobs.

Since the new jab managed to build a strong immunity in only a fifth of mice, researchers concluded that their vaccine must be further improved.

"We don't even know yet if it will work in humans, but it's certainly a significant step in efforts to create a better TB vaccine," Jacobs said.

source: worldhealthorg.