A study by Stellenbosch University scientists has shown that certain people's immune systems react differently when exposed to the bacteria that cause tuberculosis (Mycobacterium tuberculosis or Mtb) than others.
This research, recently published in The Lancet's EBioMedicine journal, brings scientists one step closer to finding ways of preventing people from developing the disease. People living with HIV are at increased risk of TB, and it is particularly significant that the researchers found this immune reaction in some people living with HIV as well.
The study challenges paradigms about what happens after people are infected with Mtb, said Professor Marlo Möller with the Division of Molecular Biology and Human Genetics at Stellenbosch University's Faculty of Medicine and Health Sciences.
“In the past we had a simpler view of what happens after Mtb infection, but the study changes this," said Möller, the senior author of the manuscript. The field work was led by her colleague, Dr Elouise Kroon, with Prof Eileen Hoal as the local Principal Investigator.
The study shows that the tests commonly used to infer Mtb infection are not always able to detect infection in all people. “Not everyone will give a positive test when they've been in contact with the bacteria. Our study has shown some people who test negative have antibodies against the bacteria so they have been in contact with it and maybe the immune system is dealing with it in a different way," Möller said.
Elaborating on the significance of the manuscript, she said: “This research brings us a step closer to understanding why some people, even though they were exposed to and infected with Mtb, do not go on to develop active tuberculosis. If we can figure that out, we may be able to prevent people from developing active disease after being infected.
“It is important to understand all the processes that happen when you get infected with Mtb and this research assists with this. Understanding the mechanisms of resistance will enable us to develop TB prevention and treatment modalities."
Möller said it was also significant that the study looked at the two tests commonly used to infer Mtb infection. “They are not a direct test to say you definitely have the bacteria in you. Instead they test the immune system to see if it recognises the bacteria which determines if it has been in contact with the bacteria before.
"It is significant because these persons may have possible alternative mechanisms of clearing infection and preventing progression to TB disease."
Reacting to the news of the acceptance of the manuscript, Möller said it was very satisfying to see the work of herself and her colleagues in such a prestigious journal.
“It is always a highlight to get a manuscript accepted. This is what we work towards to contribute to the body of science out there and to improve the health of people. It's the crown on your hard work and the long hours you put in and the challenges you face."
Below are links to more information on the research:
Caption: Nosipho Mtala, Elouise Kroon, Sihaam Boolay, Marlo Möller, Craig Kinnear. Insert: Profs Eileen Hoal & Gerhard Walzl.