A newborn fawn laying in a flowering meadow takes its first wobbly steps and soon gleefully frolics. Unbeknownst to the little fawn, a mountain lion intently watches the little morsel. Fortunately, the fawn’s mother knows the world is full of danger and guides her little one to safety.
Although we do not have to worry about being a mountain lion’s next meal (although it occasionally happens), the world still contains many dangers. If we do not want to share the would-be fate of the little fawn, we need our very own sentinels. This could not be truer when it comes to infectious diseases. Too recently, we observed how a small outbreak of a disease, such as Zika or Ebola, can quickly become an epidemic. If these are caught early, then fewer people suffer or lose their lives.
How can we enlist sentinels to stand watch? One way involves the creation of tests that can determine if a person is at risk of developing a serious illness, such as tuberculosis. A person possessing a latent tuberculosis infection (LTBI—i.e., with no obvious symptoms) could eventually develop an active tuberculosis infection that easily spreads. If these individuals can be identified and treated early, then the chance of transmission drops. The tuberculosis tests currently on the market are plagued by false positive results. A highly accurate test is crucial for preventing the global spread of this disease that affects 2 billion people.
Developing an improved assay to identify who is at risk of developing an active tuberculosis infection has been the work of a team of Colorado researchers (De Groote et al., 2017). The group focused on identifying biomarkers indicative of LTBI. The scientists used the SOMAscan® assay to identify biomarker candidates from people who either tested positive (confirmed LTBI) or negative (no LTBI) in three commercially available tuberculosis tests. The group identified several strong protein biomarker candidates and confirmed interferon gamma (IFN-g), a biomarker identified in previous studies. Using IFN-g alone, they could not definitively separate healthy people from those with LTBI (still had false positives). By including another biomarker (interleukin-2) in the search, they could accurately distinguish the LTBI individuals.
Although this work is preliminary, it is a significant step forward in the development of a reliable LTBI test. Thanks in part to the stability of SOMAmer® reagents, we can envision a test that could be readily deployed in remote villages to identify people with latent infections and get them the treatment they need. With this kind of sentinel, tuberculosis infections may become globally eradicated. Also, it will be one less mountain lion-esque danger that we must be concerned about as we frolic through the meadows of life.
De Groote, M. A., Higgins, M., Hraha, T., Wall, K., Wilson, M. L., Sterling, D. G., . . . Belknap, R. (2017). Highly Multiplexed Proteomic Analysis of Quantiferon Supernatants To Identify Biomarkers of Latent Tuberculosis Infection. J Clin Microbiol, 55(2), 391-402. doi:10.1128/JCM.01646-16