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Tuberculosis Bacteria Outsmart the Immune System
Tuberculosis bacteria employ an unusual strategy. They present themselves to the immune system in a constant shape. Their antigenic variation is low what provokes a severe immune response. As a consequence, the bacteria enter the lungs from where they are easily transmitted from humans to humans by coughing as researchers from the Swiss Tropical and Public Health Institute (Swiss TPH) and the University of Basel show in the current issue of Cell Host & Microbe.
23 October 2015
There is a continuous “arm’s race” between immune systems and pathogens. The immune system develops antibodies against invading germs such as bacteria, viruses or parasites. These, in turn, answer with antigenic variation, i.e. they change their traits to undergo immune response. Most of the pathogens profit from this basic mechanism in infection biology.
Antigen conservation as a hallmark of Mycobacterium tuberculosis
The Mycobacterium tuberculosis, the pathogen causing tuberculosis in humans, diverges from this pattern. Its antigens recognised by the immune system exhibit similar traits between different strains and are hyperconserved as scientists from Swiss TPH and the University of Basel show. “The almost lack of antigenic variation possibly created an evolutionary advantage for the TB-bacteria” says Sébastien Gagneux from Swiss TPH and co-author of the study.
For, during a TB-infection, these highly conserved antigens provoke a severe immune response that enables the bacteria to enter the lungs from where they are easily transmitted from humans to humans by coughing.
Possible new targets for a new TB-vaccine
The scientists draw their conclusions from a genome analysis of 216 different tuberculosis strains. Also, they identified seven TB-antigens that are not conserved but highly variable and that trigger an immune response in TB-patients. These exceptions could be possible targets for the development of a new TB-vaccine. For traditional vaccine candidates are based upon the highly conserved antigens that serve the ultimate aim of the pathogens.
“But to stimulate the immune system with an antigen that favours the bacteria is probably not the best strategy”, says Gagneux with regard to tradition vaccine development strategies. Therefore, the newly gained insights could possibly open up a new avenue for developing an effective TB-vaccine.
Original source
Mireia Coscolla, Richard Copin, Jayne Sutherland, Florian Gehre, Bouke de Jong, Olumuiya Owolabi, Georgetta Mbayo, Federica Giardina, Joel D. Ernst, and Sebastien Gagneux
M. tuberculosis T Cell Epitope Analysis Reveals Paucity of Antigenic Variation and Identifies Rare Variable TB Antigens
Cell Host & Microbe (2015), doi: 10.1016/j.chom.2015.10.008
Further information
- Prof. Dr. Sébastien Gagneux, Swiss Tropical and Public Health Institute, Head of Tuberculosis Research, email: sebastien.gagneux@unibas.ch
- Dr. Christian Heuss, Swiss Tropical and Public Health Institute, Head of Communications, Tel +41 61 284 86 83, email: christian.heuss@unibas.ch
