Genomic hybrid capture assay to detect Borrelia burgdorferi: an application to diagnose neuroborreliosis in horses

By Thomas J. Divers

Borrelia burgdorferi, the causative agent of Lyme disease, is transmitted to horses and other mammals by infected Ixodes ticks, often called “deer ticks”. In Lyme endemic areas, B. burdorferi infection in horses is common and a low percentage of infected horses will develop clinically apparent Lyme disease. Neuroborreliosis, or more aptly referred to as Neurologic Lyme disease, is a neurologic form of Lyme disease occurs in horses with most cases diagnosed by autopsy. The ante-mortem diagnosis of Neurologic Lyme disease in horses is difficult as the disease can mimic several other diseases of the nervous system. In addition, the detection of B. burgdorferi in the cerebrospinal fluid (CSF) of diseased horses is difficult since low numbers of the organism are present in the fluid and routine molecular diagnostic techniques such as polymerase chain reaction (PCR) have a low sensitivity for B. burgdorferi detection in CSF.

In a recent article published in the Journal of Veterinary Diagnostic Investigation, we highlight a newer and what we believe is a more sensitive testing methodology for detecting B. burgdorferi DNA in the CSF of an adult horse with Neurologic Lyme disease. The affected horse resided in a Lyme endemic area and had an acute onset of fever, severe depression, incoordination of gait and increased sensitivity to being touched. CSF collected from the horse had a marked increase in white blood cells suggesting an infectious cause of the disease but extensive testing for numerous bacterial, protozoal and viral diseases, including PCR for B. burgdorferi, failed to reveal a cause. Oxytetracycline treatment for Neurologic Lyme disease began on day 3 after ruling out other infectious diseases. After 14 days of intravenous administered oxytetracycline, antibiotic treatment with orally administered minocycline continued for an additional 60 days. The horse showed gradual improvement returning to high-level athletic competition 5 months later.

Retrospectively, the author collaborated with researchers at Rutgers University and the University of Maryland Schools of Medicine to use a newly researched and more sensitive test to determine if the affected horse had Neurologic Lyme disease. Stored frozen spinal fluids from the affected horse and a normal control horse were tested for the Lyme organism and other bacterial pathogens using a B. burgdorferi hybrid capture probe and next-generation sequencing (NGS). The hybrid capture probe enriches DNA of B. burgdoferi in the sample if the organism is present. Following DNA enrichment, NGS of the sample captures the mass of the sample DNA and analyzed for known pathogens. Recent research has found this testing methodology improves the detection for B. burgdorferi in CSF in other species. Results of the testing in this equine case confirmed that B. burgdoreri DNA was present in the CSF sample from the affected horse and comprised over 63% of the captured DNA. Borrelia burgdorferi DNA was absent in the control horse CSF.

This horse study demonstrated that the hybrid capture probe/NGS testing could be helpful for detecting B. burgdorferi in the CSF of horses, thus improving the ability to diagnosis Neurologic Lyme disease and allowing early, focused treatment for the disease. To my knowledge, hybrid probe capture/ NGS is not currently commercially available at veterinary diagnostic laboratories but, due to the low cost of the hybrid capture probes and the increasing use of expedited NGS in diagnostic laboratories, the hope is that this testing methodology will be further evaluated for clinical use in horses and other species.

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Article Details

Genomic hybrid capture assay to detect Borrelia burgdorferi: an application to diagnose neuroborreliosis in horses
Thomas J. Divers, Emmanuel F. Mongodin, Christopher B. Miller, Rodney L. Belgrave, Rachel B. Gardner, Claire M. Fraser, and Steven E. Schutzer
First Published July 21, 2022
DOI: 10.1177/10406387221112617
Journal of Veterinary Diagnostic Investigation

About the Author

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Dr. Divers is the Rudolph J. and Katharine L.Steffen Emeritus Professor of Veterinary Medicine at Cornell University. He earned his DVM from the University of Georgia and became a diplomat of both the American College of Internal Medicine and the College of Emergency and Critical Care. His clinical passion has been in providing medical care for horses and dairy cattle and his research has included collaborative studies on equine liver, kidney and nervous system diseases in addition to studies on Lyme disease and leptospirosis. Dr. Divers has been the recipient of teaching awards at four universities, received the Educator of the Year Award from both the AAEP and ACVECC, the ACVIM Robert W. Kirk Award for Professional Excellence, the Cornell University Hospital for Animals Distinguished Service Award for service to referring veterinarians and inducted into the University of Kentucky Equine Research Hall of Fame. Dr. Divers is retired but still enthusiastically consults on cases, research projects and teaches classes.