How does the Lyme vaccine work?

(by special request) :-)

Hey, I actually know this one!

So, Lyme disease is caused by the bacterium Borrelia burgdorferi which is transmitted by several species of ticks. The bacterium expresses several different antigens depending on where the bacterium is existing. I think that the bacterium expresses the OspA antigen when the bacterium is living in the tick, and the OspC antigen when the bacterium is living in the mammalian host (dog, human, etc.).

The Lyme vaccine, when administered to a dog, induces the dog's immune system to make antibodies against the OspA antigen. (Seems counterintuitive because the OspA antigen isn't expressed in the dog, right?)

The deal is that the tick must be attached to the mammalian host and feeding for a certain period of time before the bacterium can be transmitted.

When the tick starts taking a blood meal from the dog, it also ingests the antibodies against OspA that are circulating in the dog's bloodstream thanks to the vaccination.

The antibodies against OspA then enter the tick's digestive organs where the bacterium is waiting before it can be transmitted to the dog. Since the bacterium is still expressing the OspA antigen, the antibodies against OspA can bind up the OspA antigen and neutralize it and thus prevent it from being transmitted to the dog.

(At least that's how it works in theory.)

Whoa, I learned something in vet school!!!