Lyme vaccine by Yale University shows promise

A novel vaccine for Lyme disease shows promise with its creators from Yale University showing that the vaccine offers protection against the disease in guinea pigs.

The vaccine offers protection against infection by the bacterium that causes Lyme disease and may also combat other tick-borne diseases. The findings have been published in the journal Science Translational Medicine.

The vaccine takes a different approach than traditional vaccines that trigger an immune response. In the new vaccine, instead of triggering an immune response against a particular pathogen, the new vaccine prompts a quick response in the skin to components of tick saliva, limiting the amount of time that ticks have to feed upon and infect the host, the study shows. The vaccine is delivered by the same mRNA technology that has proved so effective against COVID-19.

The saliva of the black-legged tick Ixodes scapularis, which transmits the Lyme disease pathogen Borrelia burgdorferi, contains many proteins. The investigators focused on 19 separate proteins.

Researchers analyzed bits of mRNA that produce all 19 of the saliva proteins. A similar strategy was used in vaccines that effectively combat the SARS-Cov-2 virus. And in a series of experiments, they tested the vaccine on guinea pigs, which can be infected with the Lyme disease agent and have also been used as a model to study tick resistance.

Unlike non-immunized guinea pigs, vaccinated animals exposed to infected ticks quickly developed redness at the tick bite site. And as long as ticks were removed when redness appeared, none of the immunized animals developed Lyme disease. In contrast, about half of the control group became infected with B. burgdorferi after ticks were removed. When a single infected tick was attached to immunized guinea pigs and not removed, none of them was infected while 60% of control animals did become infected. If three ticks remained attached to the guinea pigs, however, protection waned even in immunized animals.

In addition, ticks attached to immunized animals were unable to feed aggressively and dislodged more quickly than those on guinea pigs in the control group.

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