There is no escaping them: Ticks are everywhere in Massachusetts. The state had one of the highest infection rates of Lyme disease in the country last year, with 3,646 reported cases.
Lyme disease can be successfully treated with antibiotics — if it’s detected. One-quarter of people don’t develop the characteristic bull’s-eye rash following the bite of an infected tick, and untreated infection can lead to debilitating symptoms such as arthritis and nerve pain.
A vaccine to prevent Lyme disease was pulled from pharmacy shelves in 2002 by manufacturer GlaxoSmithKline amid poor sales and alleged safety concerns, and there has been no replacement. Now, researchers at the University of Massachusetts Medical School are trying to develop an alternative way to prevent infection: a drug that could be administered to those at risk annually, just before tick season.
Though it sounds like the flu shot, the drug is not a vaccine, which activates the immune system against an invader. Instead, it is a pre-exposure prophylaxis, a molecule ready to kill bacteria immediately, similar to pills taken to ward off malaria when traveling abroad. “You take the medicine before you’re going to be exposed,” says lead researcher Mark Klempner, executive vice chancellor at MassBiologics, the nonprofit drug research and manufacturing arm of UMass.
Klempner and colleagues presented positive results from mouse studies at two infectious disease conferences last month, but the details have yet to be reviewed by other scientists or published.
The drug is a monoclonal antibody, a small molecule that binds to only one substance. In this case, the antibody binds and kills the bacteria in the gut of infected ticks that cause Lyme disease.
An antibody has several potential advantages over the previously withdrawn vaccine against Lyme disease, which required three doses over six months to achieve full protection and was only approved for those 15 to 70 years old. Klempner expects an antibody to provide immediate protection and be safe for all ages, including children.
To find the drug, the researchers injected mice engineered to produce human antibodies with proteins from Borrelia burgdorferi, the bacteria that causes Lyme disease in North America. Out of 593 human antibodies isolated from the mice, they narrowed the group down to four that are highly potent against B. burgdorferi and two other Borrelia species that cause Lyme disease in Europe.
Those final four were then tested in mice bitten by six infected ticks. “All four of them, at a certain dose, provided 100 percent protection compared to an irrelevant antibody,” says Klempner.
Finally, the team identified the antibody with the longest circulation time, hoping it will provide at least six months of protection in humans, and are now testing that drug’s safety in animal tissues and organs. Klempner hopes to initiate human clinical trials as early as 2016.