Summary: the tests were conducted on guinea pigs because they can develop immune reactions to repeated tick bites like humans do. Mice do not seem to be suited for that for once.
The vaccine was administered intradermally. It consists of nucleoside-modified mRNA encapsulated in lipid nanoparticles like we know them from Covid vaccines already. The contained mRNA sequences encode 19 different proteins that are usually found in the saliva of a particular kind of tick in the US. These proteins were selected because of prior research it was known that they seemed to cause inflammatory reactions in the host. The inflammatory reaction that occured at the site of the tick bite hampered feeding of the ticks and reduced risk of disease transmission. The vaccine mostly seems to buy more time to remove the ticks before an infection can take place because the disease causing bacteria was not directly targeted by the vaccine.
The vaccine was administered intradermally. It consists of nucleoside-modified mRNA encapsulated in lipid nanoparticles like we know them from Covid vaccines already. The contained mRNA sequences encode 19 different proteins that are usually found in the saliva of a particular kind of tick in the US. These proteins were selected because of prior research it was known that they seemed to cause inflammatory reactions in the host. The inflammatory reaction that occured at the site of the tick bite hampered feeding of the ticks and reduced risk of disease transmission. The vaccine mostly seems to buy more time to remove the ticks before an infection can take place because the disease causing bacteria was not directly targeted by the vaccine.