Publication: The Platelet Fraction is a Novel Reservoir to Detect Lyme Borrelia in Blood
Open Access: Click here to download the manuscript for free
Authors: Victoria P. Sanderson, Iain L. Mainprize, Lisette Verzijlenberg, Cezar M. Khursigara and Melanie K. B. Wills
What: The laboratory test for Lyme Disease is serological, meaning scientists presently use the serum portion of blood to look for evidence of an immune response against the pathogen, Borrelia burgdorferi. This research project focused on how to best detect or extract Borrelia directly from blood, first by analyzing existing methods and protocols, and then by using experimentally infected human blood to identify the optimum processing conditions and fractions that increase the yield of Borrelia.
Lead study author Victoria Sanderson handles blood samples in the G. Magnotta Lab biosafety cabinet.
Who: This study was a major component of Victoria Sanderson’s Master of Science (MSc) thesis work, with contributions from other members of the G. Magnotta lab and colleagues from the Department of Molecular and Cellular Biology. We’re also grateful to our blood donors, and the phlebotomy team in the Department of Human Health and Nutritional Sciences University of Guelph.
Why: Lyme disease, caused by a bite from an infected tick, is a growing public health threat that requires more rapid and sophisticated laboratory diagnostics. The early stage of the infection can present as nonspecific flu-like symptoms and under certain conditions a rash may also appear. Prompt detection and antibiotic treatment of Lyme in the early stages of disease provides the best prognosis, although symptoms may reoccur and evolve in up to one third of patients.
Without adequate early intervention, Borrelia can affect vascular and lymphatic systems including the nervous system and heart, giving rise to serious symptoms that can resemble other diseases which can complicate diagnosis.
The standard laboratory test for Lyme disease consists of a two-tiered serological assessment that has both biological and technical limitations. Improving techniques for finding Borrelia in the blood could potentially help speed up the diagnosis process and provide more opportunity for Borrelia detection.
This study also has important implications for biomedical research. In order to understand more about how Borrelia affect the human body and study the strains of the bacteria that are causing disease in people today, it is critical for researchers to be able to recover the pathogen from patients. Our findings suggest a new way of accessing Borrelia in the circulatory system without exposing the bacteria to chemicals that damage them.
Our results show that the platelet fraction of blood contains more Borrelia than the plasma, which is usually used in blood tests.
How: To find out present protocols for detecting Borrelia in the blood, a comparison of clinical culture protocols was done by compiling studies involving Borrelia burgdorferi where a blood based clinical culture was used and where both the inoculation source and collection tube were clearly indicated. The information collected provided an assessment of present methods of Borrelia detection to be used as a basis of determining how the project experiments would be conducted.
We then conducted our own experiments using whole blood taken from healthy donors and infected with Borrelia in the lab. We looked at the impact of chemicals that are used to prevent blood from clotting (anticoagulants), centrifugation (spinning blood to separate components), and whether Borrelia assort with a particular cell fraction. We confirm that the most common anticoagulant (EDTA; lavender top blood tubes) are harmful to Borrelia, and suggest another way of collecting whole blood for Borrelia analysis (citrate; blue top tubes). Contrary to popular protocol, we found that the richest source of Borrelia was the platelet fraction, not the liquid componet (serum or plasma) that is usually analyzed. This opens doors to test an unconventional fraction in patient blood, to potentially increase sensitivity of molecular assays.
What’s next: Now that we have a technical proof-of-concept using lab-infected donor blood, we need to test whether these observations hold true in patients. Ideally, a diagnostic test should perform well across all stages of disease (early to late), so we would like to evaluate a range of Lyme cases.