Ninety-five percent of dogs exposed to Lyme disease do not have symptoms, according to the Centers for Disease Control (CDC). And according to a recent study, their immune systems may be tricked into not launching a full-blown response or developing lasting immunity to the disease. 

The study, by researchers at the University of California, Davis (UC Davis), was published in PLOS | Pathogens on July 2.

“We demonstrated that an animal infected with Borrelia burgdorferi, the corkscrew-shaped bacteria that cause Lyme disease, launches only a short-lived immune response, and that protective immunity against repeat infections quickly wanes,” said Nicole Baumgarth, DVM, PhD, and a professor in the School of Veterinary Medicine. Baumgarth is an authority on immune response to infectious diseases at the UC Davis Center for Comparative Medicine.

“This study also suggests a possible mechanism responsible for the disappearance of antibodies following infection and subsequent treatment with antibiotics,” Baumgarth said.

The Borrelia burgdorferi bacteria initially trigger a strong immune response in an infected animal, but findings from this study indicate that the bacteria soon cause structural abnormalities in “germinal centers” — sites in lymph nodes and other lymph tissues that are key to producing a long-term protective immune response.

For months after infection, those germinal centers fail to produce the specific cells — memory B cells and antibody-producing plasma cells — that are crucial for producing lasting immunity.

In effect, the bacteria prevent the animal’s immune system from forming a “memory” of the invading bacteria and launching a protective immune response against future infections.

The researchers found that following Borrelia burgdorferi infection, this process even prevented induction of strong immune responses to an influenza infection.

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