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
