Lyme disease is the most common tick-born disease in the United States, with almost half a million cases diagnosed every year. Lyme disease is caused by the bacterium Borrelia burgdorferi (Bb), which is transmitted to humans when they are bitten by an infected tick. Bb does not produce any toxins, and the pathogenesis of Lyme disease in humans appears to be due to a strong immune response to the bacterium itself. The resulting long-lasting inflammatory response can damage several different organs including the brain, peripheral and central nervous systems, heart, and joints.
When Bb infection is recognized immediately, usually by a characteristic bullseye shaped rash around the site of the tick bite, Lyme disease can usually be cured by treatment with antibiotics. However, 20% to 30% of people with Lyme disease will not have the rash, and many will not know they are infected in time to be cured. This has led to a great interest in developing a vaccine to prevent Lyme disease.

Figure 5A from Hove PR, Magunda F, de Mello Marques MA, et al. (2021) PLoS ONE. 16(6):e0252214. Licensed under CC BY 4.0.