Why some strains of Lyme disease bacteria are common and others are not

Dec 04, 2012

New clues about the bacteria that cause Lyme disease could lead to a novel strategy to reduce infections, according to a study to be published in mBio, the online open-access journal of the American Society for Microbiology, on December 4.

The study reveals that the of the white-footed mouse, a very common reservoir for (the that causes the disease), responds differently to different strains of the bacterium, a finding that will help scientists tweak the animals' immune systems to prevent infection. A vaccine that keeps these wild mice free of the pathogen could significantly curb the spread of the disease from mice to to humans.

"There's no human vaccine, and there's not likely to be one," says Alan Barbour of the University of California, Irvine, the lead author of the study. "We have to focus on lowering the risk. One way to do that is by treating the animals that carry the disease." offers a good example of how this might be accomplished, says Barbour. By deploying vaccine-laced food bait, have managed to lower the rabies infection rate in wildlife and significantly limited the spread of the disease to pets and humans.

Although only emerged in the U.S. in the past 40 years or so, around 25,000 cases are now reported every year in this country and the of these cases are estimated to range in the billions of dollars. Despite the growing importance of the disease, little is known about the evolution and ecology of the bacterium that causes the illness.

Barbour and his colleagues sought to understand why as many as 15 different strains of B. burgdorferi exist in the wild at differing degrees of prevalence. In the parts of the country where Lyme disease is most common, the majority of white-footed mice are infected with B. burgdorferi during the course of the year. Unlike humans and , white-footed mice don't get sick when they're infected so the bacteria grow and multiply within them, and when a deer tick bites it sucks up the bacteria along with its blood meal.

In the lab, the group at UC Irvine exposed white-footed mice to various strains of B. burgdorferi and tracked the course of the infection. All the B. burgdorferi strains infected the white-footed mice, but some strains managed to grow to high densities in various mouse tissues while others did not.

Barbour says the immune reactions the mice mounted against the various strains explain these discrepancies: the greater the immune response, the fewer bacteria found in a mouse's tissues and vice-versa. Importantly, the strains that grew to greatest densities within the mice are also the strains that are most prevalent in the wild.

When they looked at the immune reaction to individual B. burgdorferi proteins the authors found a complex interplay of reactivities. The mice reacted in different degrees to the various proteins present in a single bacterial strain, which could explain why such a great diversity of B. burgdorferi strains are sustained in the wild, say the authors.

Barbour says knowing more about how the white-footed mouse reacts to all the various B. burgdorferi strains and immunogenic proteins will help vaccine developers select the best proteins to put in a vaccine. "The best candidate for the mouse vaccine is something that's the same in all the [B. burgdorferi] strains," he says.

Once a vaccine for the white-footed mouse is developed, it will need to be tested by exposing immunized mice to a selected set of diverse B. burgdorferi , says Barbour, and the results of this study can help make that selection. "If we can find five that are representative, that would be an advantage."

This study, he says, "is going to provide a foundation for future studies in understanding the infection in these animals as we proceed with developing vaccines."

Explore further: Microbes provide insights into evolution of human language

add to favorites email to friend print save as pdf

Related Stories

Lyme disease bacteria take cover in lymph nodes

Jun 16, 2011

The bacteria that cause Lyme disease, one of the most important emerging diseases in the United States, appear to hide out in the lymph nodes, triggering a significant immune response, but one that is not strong enough to ...

Lyme disease surge predicted for the northeastern US

Mar 16, 2012

The northeastern U.S. should prepare for a surge in Lyme disease this spring. And we can blame fluctuations in acorns and mouse populations, not the mild winter. So reports Dr. Richard S. Ostfeld, a disease ...

Birds Play an Important Role in the Spread of Lyme Disease

Dec 23, 2009

(PhysOrg.com) -- The range of Lyme disease is spreading in North America and it appears that birds play a significant role by transporting the Lyme disease bacterium over long distances, a new study by the Yale School of ...

Recommended for you

Cell division speed influences gene architecture

21 hours ago

Speed-reading is a technique used to read quickly. It involves visual searching for clues to meaning and skipping non-essential words and/ or sentences. Similarly to humans, biological systems are sometimes ...

Secret life of cells revealed with new technique

23 hours ago

(Phys.org) —A new technique that allows researchers to conduct experiments more rapidly and accurately is giving insights into the workings of proteins important in heart and muscle diseases.

In the 'slime jungle' height matters

Apr 23, 2014

(Phys.org) —In communities of microbes, akin to 'slime jungles', cells evolve not just to grow faster than their rivals but also to push themselves to the surface of colonies where they gain the best access ...

Queuing theory helps physicist understand protein recycling

Apr 22, 2014

We've all waited in line and most of us have gotten stuck in a check-out line longer than we would like. For Will Mather, assistant professor of physics and an instructor with the College of Science's Integrated Science Curriculum, ...

User comments : 0

More news stories

Phase transiting to a new quantum universe

(Phys.org) —Recent insight and discovery of a new class of quantum transition opens the way for a whole new subfield of materials physics and quantum technologies.

Imaging turns a corner

(Phys.org) —Scientists have developed a new microscope which enables a dramatically improved view of biological cells.

Sensors may keep hospitalized patients from falling

(Medical Xpress)—To keep hospitalized patients safer, University of Arizona researchers are working on new technology that involves a small, wearable sensor that measures a patient's activity, heart rate, ...