Tuberculosis is a major global public health problem. Treatment often takes many months and till this day there is no effective vaccine. Various TB bacterial strains exist globally, with different geographical spread. Only the so-called Lineage 4 occurs on all continents. It is responsible for the majority of the 10 million new infections and 2 million deaths annually.
A team of 75 scientists at 56 institutions analyzed the genetic make-up of TB bacteria from several thousand patients. Surprisingly, it was found that Lineage 4 can be genetically further subdivided into several sublineages. Some of these sublineages occur all over the world, others are geographically highly restricted. According to the study in the journal Nature Genetics, TB bacteria can be divided into generalists with worldwide distribution and specialists that have focused on localized ecological niche. While ecologists have been differentiating between generalists and specialists, especially in plants, for a pathogen that transmits exclusively from human to human, such a subdivision is new.
These new findings have implications for the development of new TB vaccines. The more TB bacteria can adapt their antigens, the more difficult it will be to design a vaccine that is equally effective in all human populations across the world.
For further details see:
David Stucki, Daniela Brites, Leïla Jeljeli et al Mycobacterium tuberculosis lineage 4 comprises globally distributed and geographically restricted sublineages. Nature Genetics, 2016; DOI: 10.1038/ng.3704
Posted by Dr. Tim Sandle