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The vaccine doesn't trigger the immune system to attack B. burgdorferi. Instead, it prompts a quick response in the skin to certain proteins in tick saliva, which reduces the amount of time a tick has to infect the host, the Yale University team explained.
"The vaccine enhances the ability to recognize a tick bite, partially turning a tick bite into a mosquito bite," said senior author Dr. Erol Fikrig, a professor of medicine and epidemiology at Yale, in New Haven, Conn.
"When you feel a mosquito bite, you swat it," he explained. "With the vaccine, there is redness and likely an itch so you can recognize that you have been bitten and can pull the tick off quickly, before it has the ability to transmit B. burgdorferi."
Compared to unvaccinated guinea pigs, those that were vaccinated quickly developed redness at a tick bite site. As long as ticks were removed when redness appeared, none of the vaccinated guinea pigs were infected. About half of the unvaccinated guinea pigs became infected after ticks were removed, the findings showed.
When a single infected tick was attached to vaccinated guinea pigs and not removed, none was infected, compared with 60% of unvaccinated guinea pigs. But if three ticks remained attached to vaccinated guinea pigs, their protection wasn't as strong, according to the report published Nov. 17 in the journal Science Translational Medicine.
The researchers also found that ticks attached to vaccinated guinea pigs were unable to feed aggressively and dislodged more quickly than those on unvaccinated guinea pigs.
At least 40,000 cases of Lyme disease are reported each year in the United States, but the actual numbers of infections could be 10 times greater, the researchers noted. Other tick-borne diseases have also spread in many areas of the United States, they added.
"There are multiple tick-borne diseases, and this approach potentially offers more broad-based protection than a vaccine that targets a specific pathogen," Fikrig said in a university news release.
"It could also be used in conjunction with more traditional, pathogen-based vaccines to increase their efficacy," he added.
More research is needed to discover ways that proteins in saliva can prevent infection, Fikrig said, and human clinical trials would be needed to assess the vaccine's effectiveness in people.
The American Academy of Family Physicians has more on Lyme disease.
SOURCE: Yale University, news release, Nov. 17, 2021
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