Modified bacteria could hold TB vaccine potential

A team of scientists from the United States has shown that an injection of modified bacteria related to those causing tuberculosis could potentially protect against the lung disease.

Animal experiments demonstrated that, in some cases, TB can be completely eliminated with the new vaccine, according to the BBC.

The only TB vaccine currently seen as being effective, BCG, has severe limitations. In different parts of the world it has been shown to be between zero and 80 percent effective.

The nonprofit group TB Alert said that the new research is still in its early stages and that any potential for a new human vaccine to result from it is unknown, the BBC reports. Furthermore, there would most likely be potential problems related to giving the new vaccine to some at risk patients.

A team of scientists from the Albert Einstein School of Medicine in New York was working with a cluster of genes called esx-3 found in the bacterium that causes TB. Variants of esx-3 are found in all of the bacteria from the family Myobacterium, including Myobacterium tuberculosis. The genes help the organism evade detection by immune systems.

Myobacterium cannot live without esx-3 genes, but a relative, M. smegmatis, can. The team tried removing the genes and then injected what should have been a deadly dose into mice. Within days, the mice were able to clear the infection, leading the researchers to believe that they were onto something.

They then tried putting the esx-3 genes from M. tuberculosis into M. smegmatis, calling the result Ikeplus. Mice injected with Ikeplus cleared the resultant infection and were later found to have an increased immunity to M. tuberculosis.

"We consistently protected mice better with Ikeplus than with BCG,” Dr. William Jacobs, the team’s leader, said, the BBC reports. “This is something we've dreamed about for years, to be able to get longer protection and bactericidal immunity."

Jacobs warned, however, that only 20 percent of the mice survived long-term, so any vaccine to result from the findings needs more time in development.