A study has found that it is possible to block summer's unwanted guest, ticks, with a vaccine. It revealed that individuals with resistance have a unique immune response that prevents ticks from remaining attached for long periods of time, and an mRNA vaccine modeled after this is currently under development.
The research team led by Erol Fikrig, a professor of microbiology at Yale University, published research findings in the international journal "Science Translational Medicine" on the 26th (local time), revealing how the immune responses of those who do not allow ticks to adhere differ from those of others.
Ticks are parasites that attach to the skin and suck blood with their hook-shaped sharp mouthparts. They are only about 2 to 3 millimeters long, smaller than an adult fingernail, but they have a powerful adhesive strength similar to cement, allowing them to adhere firmly to the skin. In this process, they transmit various pathogens that cause diseases, including Lyme disease.
Scientists have been researching for decades to understand how ticks penetrate the human immune system and transmit pathogens. The key lies in the proteins secreted by ticks while they feed on blood. Ticks interfere with the human immune response using specific proteins to conceal themselves. This is also why most people do not notice when they are bitten by a tick.
On the other hand, some individuals have shown an immune response to the proteins secreted by ticks. As a result, the adhesive strength of the tick weakens, and the area where the tick has attached becomes red more quickly, causing discomfort and leading to earlier removal compared to others.
The research team analyzed the response of human immune cells, specifically antibodies, binding to over 3,000 tick antigen proteins. As a result, they identified specific tick antigens recognized by the immune systems of individuals with tick resistance. They used guinea pigs to verify immunity against ticks.
After injecting guinea pigs with the blood of individuals with tick resistance and then attaching ticks to their bodies, the researchers explained that the rate at which ticks fell off within two hours was higher in guinea pigs that received resistant blood than in those injected with normal blood.
The research team also created an experimental mRNA vaccine using genes from 25 tick antigens. Immune responses to ticks were observed in the group of guinea pigs that received the vaccine. The researchers believe that this study has a high potential to lead to future mRNA vaccine development.
In the U.S., dozens of people die every year from Lyme disease caused by ticks. Lyme disease causes conditions such as encephalitis, peripheral neuropathy, and myocarditis. In South Korea, another tick-borne infectious disease, severe fever with thrombocytopenia syndrome (SFTS), occurs frequently. Among 1,895 patients over a decade from 2013 to 2023, 355 died, resulting in a mortality rate of 18.7%.
Professor Fikrig is developing a tick mRNA vaccine alongside Drew Weissman, a professor at the University of Pennsylvania School of Medicine, who received the Nobel Prize in Physiology or Medicine in 2023. Professor Weissman led the development of mRNA vaccines during the COVID-19 pandemic. The two professors are searching for the most effective antigen to induce tick rejection among the 25 antigens used in the current guinea pig experiments.
References
Science Translational Medicine (2025), DOI: https://doi.org/10.1126/scitranslmed.ads9207