New Lyme Vaccines

New Lyme Vaccines

Everyone can agree that a Lyme vaccine is necessary but unfortunately funding continues to be an issue. In spite of that, there have been advances towards two very unique vaccine approaches.

The most exciting in my mind is the “spit” vaccine. The concept is that our bodies would repel the tick’s saliva literally ejecting the tick good for humans and animals. How?

Vaccines have traditionally targeted unique proteins found on the surface of pathogens. In studies published in the November 19, 2009, issue of Cell Host & Microbe, the researchers showed that it is possible to target molecules carried by a disease vector—not just the pathogen itself.

This could be an effective strategy to prevent Lyme disease, as well as malaria, dengue fever, and other diseases carried by arthropods such as ticks and mosquitoes, said senior author Erol Fikrig, a Howard Hughes Medical Institute investigator at Yale University.

When the bacterium that causes Lyme disease is transmitted to a mammal via a tick’s bite, the bacterium wraps itself in a protein cloak that makes it invisible to the host’s immune system. That cloak is made from a protein found in tick saliva, which the Lyme bacterium, Borrelia burgdorferi, causes the tick to produce in excess. In Cell Host & Microbe, Fikrig and his colleagues describe a way to turn this cloak of invisibility into a vulnerability.

Fikrig, who is chief of infectious diseases at the Yale School of Medicine, said vaccine development—even as far back as Louis Pasteur’s discoveries in the 1880s—has historically relied on using a weakened form of the pathogen, or a component of it, to evoke an immune response that would protect against later encounters with the same microbe.

“For vector-borne diseases, where the bacteria are transmitted by a tick or a mosquito, we wanted to know: Is it possible there is something that is not pathogen-based that can be targeted?” Fikrig said.

“The tick isn’t just a syringe,” Fikrig said. Tick saliva contains a variety of unsavory ingredients that help the insect’s five- or six-day blood meal proceed unnoticed by the host, and the presence of the pathogen actually changes the composition of the tick’s saliva. For example, the saliva contains anesthetics that keep the bite from stinging and blood thinners to prevent clotting.

Another approach being considered is a mice-based or properly called a “reservoir targeted vaccine” (RTV), and it’s called the Gomes-Solecki’s vaccine.

This latest vaccination efforts was conducted by Maria Gomes-Solecki of the University of Tennessee in Memphis and co-founder of the Tennessee-based company U.S. Biologic.

Using a strategy modeled after the LYMERix vaccine, which was pulled from the market in 2002 after four years of sales for allegedly causing damaging side effects, Gomes-Solecki and her team developed an oral solution with a different target: the white-footed mice.

According to her study published in The Journal of Infectious Diseases, Gomes-Solecki theorized that if young ticks ingested the blood of mice that had been vaccinated against Borrelia infection, they would ingest the mice’s antibodies against Borrelia, thereby eliminating the bacteria from the tick as well as preventing further transmission.

U.S. Biologic is currently pursuing USDA approval for their pellet vaccination, which if approved will be marketed to homeowners to sprinkle in hot-spot areas where ticks typically dwell. The pellets, Gomes-Solecki said, will be priced affordably and could be used by homeowners in conjunction with everyday rodent traps.

 

There are already successful tick vaccines towards other diseases so why not Lyme?

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