UCT TB study boosts detection

Discovery could produce tests to prevent worsening symptoms

THE DISCOVERY of a blood signal which can detect tuberculosis (TB) in those infected with HIV could change the way the most vulnerable patients are treated by enabling researchers to develop tests to prevent worsening TB symptoms.

The study, published in Proceedings of the National Academy of Sciences, was conducted by UCT honorary professor and director at the Wellcome Centre for Infectious Diseases Research in Africa, Robert J Wilkinson, together with the Francis Crick Institute, Imperial College London, and the National Institutes of Health.

The findings offer evidence of a subtle transition from latent to active TB, and could be used to test patients at risk of getting TB and treat them before they become infected and gain advanced symptoms.

“Those who are HIV infected have a higher risk of developing active TB. This signal could help us catch people at risk and treat them so that they don’t face complications,” said Wilkinson.

“We can’t put everyone on early treatment, so now we can see who is in greater risk of developing TB in a more precise way. When the disease is in its early stage, we can use fewer drugs for a shorter time. Currently there is no commercial blood test available, but we are in the early stages.”

Wilkinson explained that TB is classified as either latent or active. Latent TB occurs when a person has been infected with the bacteria, but their immune controls any further spread. They may develop active TB at a later stage, at which point symptoms become apparent.

HIV-infected patients are more likely to develop active TB, but the study which revealed the blood signal provides new insights into how the body responds in the early stages of the disease.

Wilkinson said the research team used high-resolution scans to reveal TB-related lung damage in HIVinfected patients who showed no TB symptoms. The team then built on these findings by using transcriptomics, which measure gene products called transcripts to put together a picture of what the body does to fight off a particular disease.

This was used to investigate which parts of active TB could be found in the blood of patients who were symptomless.

According to information posted by the Imperial College of London on the study, one way in which the body reacts to changes and threats is to switch genes on and off, to allow them to adapt. In patients affected by TB, this happens with several different sets of genes.

Researchers were able to take snapshots of which genes were being read in unwell people with active TB and latent TB, and by comparing them the team found certain genes were switched on during the earliest sub-clinical stages of the disease.

According to Wilkinson, with the discovery of the new signal, a blood test to detect those at risk of developing TB could be available in the next five to 10 years.

THIS COULD HELP US CATCH PEOPLE AT RISK AND TREAT THEM SO THAT THEY DON’T FACE COMPLICATIONS