French researchers have been working on an innovative vaccine that targets tick microbiota so as to indirectly reduce the bacterial load within the vector. The results of their study were published on July 24 in the journal Microbiome.
Ticks are vectors of many harmful pathogens that can cause life-threatening illnesses. Ixodes ricinus (in Europe) and Ixodes scapularis (in Canada and the United States) carry Borrelia, the bacteria that cause Lyme disease. At the moment, there is no vaccine for this disease. But that could all change, thanks to the findings of scientists at the National Research Institute for Agriculture, Food, and Environment (INRAE), in collaboration with the Agency for Food, Environmental and Occupational Health and Safety and the National Veterinary School of Alfort, France.
"Ticks can transmit a broad variety of pathogens of medical importance, including Borrelia afzelii, the causative agent of Lyme borreliosis in Europe. Tick microbiota is an important factor modulating not only vector physiology, but also the vector competence," the team reported. They focused their efforts on developing a vaccine that would disturb the tick microbiota and thus reduce Borrelia colonization.
To explore this indirect approach, they injected a harmless strain of Escherichia coli bacteria into mice, which then produced antibodies. Their reasoning was that when a tick bites one of these mice, the antibodies would pass into the arachnid's microbiota and disturb it, thereby making the tick less harmful. And indeed, the researchers' work showed that in the ticks that fed on vaccinated mice, levels of Borrelia levels were much lower than in than ticks that fed on unvaccinated mice (see video for an explanation). So, when given to a mouse, this vaccine "protects" the tick against colonization by Borrelia but does not protect the mouse against the disease.
The study has advanced this area of research in two significant ways: it provides new information on the importance of the microbiota when it comes to ticks that are infected with Borrelia, and it suggests an innovative vaccination strategy. Indeed, the results confirm that tick microbiota is essential for the development of Borrelia in the arachnid. As noted in an INRAE press release, "This is a key piece of data that opens the door to one day having an innovative vaccination strategy aimed at perturbing the microbiota of the vector of the Lyme disease agent."
This article was translated from the Medscape French Edition.
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Cite this: On the Trail of a New Vaccine for Lyme Disease - Medscape - Aug 16, 2023.