Summer is peak season for tick bites and a host of diseases that come with them. The most common tick-borne illness in the United States is Lyme disease, which affects about 476,000 people annually. Symptoms include rashes and joint pain, and they can reemerge months or even years later. One Memphis doctor is behind a recently approved vaccine for Lyme disease, and its delivery method could be used to reduce other tick-borne illnesses in the future.
The only human vaccine for Lyme disease was discontinued in 2002 due to limited demand and concerns about potential side effects. But Dr. Maria Gomes-Solecki, a professor of microbiology, immunology, and biochemistry at the University of Tennessee Health Science Center, had worked on that vaccine and believed it could continue to help reduce the spread of the disease.
“It was a great vaccine to still reuse or repurpose,” Gomes-Solecki said. “Due to the mechanism of action of the vaccine, I thought we could just do a small modification and develop the vaccine to vaccinate mice and block the transmission cycle of the bacteria, rather than using the vaccine to vaccinate people directly.”
What she developed was a new oral vaccine: not for humans, but for mice. The vaccine is delivered in the form of vaccine-coated pellets, so “it's just a question of putting a distributing device out there that allows mice to come in and nibble on a few pellets and go on about their lives,” Gomes-Solecki explained. When ingested, the vaccine neutralizes the Borrelia burgdorferi, the bacterium that causes Lyme disease, inside the mice. When a tick bites the vaccinated mouse, it too will no longer spread the disease.
“It is what we call a transmission-blocking vaccine because it prevents transmission of Borrelia burgdorferi from the tick to the mouse or from the tick to people,” Gomes-Solecki explained. “It all was really based on the fact that you vaccinated an animal that develops antibodies to the vaccine.”
Dr. Gomes-Solecki has been working on the vaccine for over 20 years, and US Biologic, a company she co-founded, has been moving it through licensing and approval processes since 2012. In May, the USDA granted the vaccine a conditional license, which is given only “to meet an emergency condition, limited market, local situation, or other special circumstance.” US Biologic is now able to market and distribute the mouse pellets to residential areas, public spaces, and pest management professionals. The company is also working with federal and state health agencies in high-risk areas, and with the USDA to receive full approval.
Lyme disease is not as prevalent in West Tennessee and Arkansas as other tick-borne illnesses, such as Rocky Mountain Spotted Fever. But Dr. Gomes Solecki hopes that the approach taken here could set a precedent for reducing the spread of similar diseases.
“We continue to work towards applying the same technology, if possible, to other diseases,” she said. “This is just the first example that it works for Lyme disease, and then we take it from there and try to apply the idea to other diseases as well.”
Still, Gomes-Solecki says the mouse vaccine is just one way to reduce the spread of Lyme disease, and it is not sufficient on its own. She is now working on a Lyme disease vaccine for humans that could be delivered intranasally.
“We still need to develop vaccines that can be applicable directly to humans,” she said. “It is when you use everything you have, all the tools available to combat Lyme disease, that you're actually going to be able to do it.”