Bacteriophages help with the early detection of Lyme disease
A new PCR test for the early detection of Lyme disease has been proposed. The test identifies a gene that does not belong to the bacterium that causes the disease, but to a bacteriophage specific to it. If a bacteriophage is found, there is also a bacterium, say scientists at the University of Leicester (UK).
Lyme disease, or borreliosis, is a tick-borne infectious disease. It is characterized by skin lesions in the form of erythema migrans, as well as lesions of the nervous system, musculoskeletal system, and heart. Lyme disease has spread over the past two decades in North America and Europe (particularly in Ukraine), and its incidence continues to rise.
Modern tests for diagnosing Lyme disease are based on detecting antibodies against the pathogen—the bacterium Borrelia burgdorferi. However, antibodies appear only a few weeks after infection. This means that early diagnosis cannot be confirmed by laboratory methods. At the same time, the first stage of the disease may be asymptomatic: without timely diagnosis and treatment, the infection will progress, and after a few months symptoms of a much more severe second stage may appear, with damage to the joints, nervous system, and others. Therefore, early diagnosis of Lyme disease is essential in people who have been bitten by a tick.
Researchers have tested* a new approach to the molecular diagnosis of Lyme disease: they decided to look not for the genome of the causative bacterium, but for a bacteriophage specific to it. They found a high correlation between the presence of a bacteriophage and B. burgdorferi in the body. At the same time, the number of bacteriophage particles in the blood of infected individuals is ten times higher than the number of B. burgdorferi bacteria, which makes it easier to identify the target gene in the PCR test.
Importantly, based on the number of copies of the terL phage gene determined by the researchers using PCR, it is possible to distinguish between the early stage (fewer copies) and later stages (more copies) of the disease. In uninfected individuals, the number of copies of the phage gene is the lowest.
The authors believe that such a test will radically change the situation regarding the early detection of Lyme disease and help prevent serious consequences of an undetected illness. In addition, the test can be used to monitor the effectiveness of Lyme disease treatments.
To introduce the test into clinical practice, it still needs to undergo a series of clinical trials and validations.
* Shan J, Jia Y, Teulières L, Patel F, Clokie MRJ. Targeting multicopy prophage genes for enhanced detection of Borrelia burgdorferi sensu lato (sl), the causative agents of Lyme disease, in blood. Front Microbiol. 2021; 12: 651217. doi: 10.3389/fmicb.2021.651217
