Researchers, including one of Indian-origin, have revealed a blood test could predict the onset of tuberculosis three to six months before people become unwell, a finding which could help better target antibiotics and save countless lives.
For the findings, published in the journal Lancet Respiratory Medicine, researchers at University College London sought to identify which, if any, gene expression signatures in blood could be used to predict the disease at a very early stage and before symptoms
Already in use for the management of some cancers
Gene expression signatures are single or combined measurements of levels of specific gene products and are being tested in a range of diseases to aid diagnosis, prognosis or prediction of the response to treatment.
Some are already being used to support the management of cancers, but none have reached the clinic in infectious diseases, such as tuberculosis (TB). "Our findings establish the gene signatures in the blood which show the most promise for identifying people who are at risk of disease," said study author Mahdad Noursadeghi, Professor at University College London.
"Future development of a blood test based on these findings could make an important contribution to efforts to reduce the impact and spread of this deadly infection," Noursadeghi added. For this study, researchers initially conducted a systematic review of published gene signatures found to be present in blood samples from people with TB, compared to healthy individuals.
Identifying gene expression signatures for TB
From this, 17 candidate gene expression signatures for TB were identified, and tested in more than 1,100 blood samples in published data sets from South Africa, Ethiopia, The Gambia, and the UK. Scientists analysed samples from people who had no TB symptoms at the time they gave blood.
Those people were then followed up to identify which participants developed TB in the subsequent months. Researchers found that eight of these signatures, including measurement of expression of a single gene, could predict the diagnosis of TB within three to six months, which falls within the accuracy required by the World Health Organisation (WHO) for new diagnostic tests.
Knowing the immune responses of patients to bacteria
This accuracy was achieved, by revealing the patients' immune responses to bacteria before the symptoms of the disease develop. "The emergence of gene expression signature tests, which can aid diagnosis and early treatment, provides real hope for the management of infectious diseases," said Indian-origin researcher and the study's lead author Rishi Gupta.
"In this study we identify multiple signatures to identify the onset of tuberculosis, which is extremely encouraging, potentially providing multiple targets for early detection," Gupta added. Further development of these tests could help identify people who will benefit most from preventative antibiotic treatment, in order to reduce the occurrence of tuberculosis, the researchers said.