Diagnosis of Latent Tuberculosis Infection: Promising Antigens

Latent tuberculosis infection (LTBI) prevalence varies dramatically by region, with one-fourth of the world's population infected. The number of people with LTBI progressing to active tuberculosis illness (aTB) should be decreased to meet the WHO End TB Strategy objective of decreasing worldwide tuberculosis incidence by 2030. Current tuberculosis (TB) diagnostic methods are based on detecting an immune response to mycobacterial antigens injected into the skin or in vitro simulations in interferon-gamma release assays. Both tests have low sensitivity, which cannot distinguish between LTBI and aTB. Therefore, various techniques, such as alternate cytokine detection and employing novel antigens, are being studied to increase the accuracy of these tests.  In addition, novel antigens can be used to monitor aTB progression and response to treatment. This review aims to assess current available diagnostic tools and evidence on novel Mycobacterium tuberculosis (Mtb) antigens for LTBI diagnosis and select the most promising antigens for future research.