Breakthrough: new TB vaccine successful in animal tests

Tuberculosis, caused by mycobacterium tuberculosis, almost results in 1.7 million deaths annually. The only preventive jab for TB is BCG that has been ineffective in substantial cases.

Now the study published in journal 'Nature Medicine' claims that by modification of the gene structure of a related bacteria, a lifelong immunity from the infection could be possible.

Genetically modified strain holds cure
Upon conducting an exhaustive study on the genetic structures of mycobacterium, scientists at the Albert Einstein College of Medicine, New York, discovered esx-3 genes, responsible for the invasion of the immune system.

Removal of the genes kills mycobacterium tuberculosis but a relative mycobacterium smegmatis, stays unaffected.

Upon injecting the genetically modified strain of M. smegmatis, from which the esx-3 genes were removed, mice that are otherwise highly vulnerable to its infection stayed unaffected and also cleared it from the system using the same T-cells that fight tuberculosis.

Experiments also included taking M. smegmatis bacteria without esx-3 and inserting M. tuberculosis esx-3 genes into it.

The resulting strain, known as Ikeplus, was injected into mice, who once again cleared the infection within three days.

Mice respond successfully
Experiments showed that mice infected with tuberculosis survived for not more than 54 days but those treated with the traditional BCG vaccine survived for 65 days.

However when the mice were dose of Ikeplus, they lived for 135 days and few lived for more than 200 days.

"This is something we've dreamed about for years, to be able to get longer protection and bactericidal immunity," stated study lead, Prof. William Jacobs.

Backing his results, Jacobs said, "vaccinated animals that survived more than 200 days had livers that were completely clear of TB bacteria, and nobody has ever seen that before."

The vaccine is under study for improvements owing to only one-fifth of mice showing complete immunity from the disease.

"Ikeplus is different from any other TB vaccine and it's a new tool for the TB arsenal," he added.