Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Bubonic Bottleneck: UNC Scientists Overturn Dogma on the Plague


The current outbreak of the plague in Madagascar shines a light on the need for new approaches to treat the ancient pathogen. A new UNC study unexpectedly unravels a long-held theory on how a fleabite leads to infection.

For decades, scientists have thought the bacteria that cause the bubonic plague hijack host cells at the site of a fleabite and are then taken to the lymph nodes, where the bacteria multiply and trigger severe disease. But UNC School of Medicine researchers discovered that this accepted theory is off base. The bacteria do not use host cells; they traffic to lymph nodes on their own and not in great numbers.

National Institute of Allergies and Infectious Diseases

Yersinia Pestis, the bacteria that cause the plague

In fact, most of the plague-causing bacteria – called Yersinia pestis – get trapped in a bottleneck either in the skin, while en route to the lymph node, or in the node itself. Only a few microbes break free to infect the lymph node and cause disease.

“Anytime you find something where the host is winning, you want to exploit it,” said Virginia Miller, PhD, professor of microbiology and immunology and senior author of the paper in PLoS Pathogens. “If we can understand how the host and the bacteria contribute to this bottleneck, then this could become something we’d target so we could either ramp up what’s causing the bottleneck or slow down the infection.”

The discovery offers much needed information about how virulent insect-borne diseases, such as plague, malaria, and dengue virus cause infection. The findings also present new routes for research on how bacterial strains cause disease despite the immune system’s best efforts.

The plague, which killed millions of people during the Middle Ages, is contracted by several people each year in the western United States. Outbreaks have occurred in the recent past in India and Africa, and one is unfolding right now in Madagascar. Standard antibiotics are effective against Y. pestis if taken early enough. But infection can go undetected for days, making diagnosis difficult and antibiotics less effective the longer the bacteria take root.

There are three kinds of plague all caused by Y. pestis: bubonic, which is contracted through fleabite; pneumonic, which is contracted by breathing in the bacteria; and septicemic, which is a severe infection of blood.

Miller’s team studies the pneumonic and bubonic versions. Three years ago, Rodrigo Gonzalez, PhD – a UNC graduate student at the time and now a postdoctoral fellow at Harvard – searched the scientific literature for data confirming the accepted notion that Y. pestis gets trafficked by human phagocytic cells from the fleabite site to the lymph nodes. Scientists readily accepted this idea because when Y. pestis microbes are added to phagocytic cells in culture, the cells do soak up the bacteria.

Phagocytes essentially eat harmful microbes, and because these cells traffic through the lymphatic system, scientists came to the logical conclusion that phagocytes take the Y. pestis to the lymph nodes.

But Gonzales and Miller knew that a fleabite does not penetrate all layers of skin like an injection does. The bites of fleas and mosquitos are intradermal; they occur within the layers of skin. Gonzales and Miller agreed that testing this long-held theory was a worthy project.

Gonzales spent months developing an accurate way to mimic the flea bite in the lab so that the proper amount of bacteria would get transferred into the skin of mice. Then Miller’s team created 10 special DNA sequences and added them to the chromosome of Y. pestis to generate 10 different strains. This did not affect virulence of the bacteria but allowed Miller’s team to tag the microbes so that the researchers could identify which bacteria traveled from the “bite site” to the lymph nodes.

“We found that only one or two of the 10 bacteria made it to the lymph node,” Miller said. “But they got there fast – within five or ten minutes after the bacteria were introduced. We know that if a bacterium is traveling in a host cell, it would not move that fast because host cells are slow; they kind of crawl through the lymphatic system instead of flowing through fluid like bacteria can.”

Miller’s team is currently conducting experiments to figure out how most of the bacteria are prevented from infecting the lymph node.

“We may have found a point of vulnerability,” Miller said. “Exploiting it could lead to new ways to defeat Yersinia pestis and other insect-borne pathogens.”

The National Institutes of Health and the Robert D. Watkins Fellowship from American Society for Microbiology funded this research.

Contact Information
Mark Derewicz
Science Communications Manager

Mark Derewicz | newswise
Further information:

More articles from Life Sciences:

nachricht ‘Farming’ bacteria to boost growth in the oceans
24.10.2016 | Max-Planck-Institut für marine Mikrobiologie

nachricht Calcium Induces Chronic Lung Infections
24.10.2016 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Oasis of life in the ice-covered central Arctic

24.10.2016 | Earth Sciences

‘Farming’ bacteria to boost growth in the oceans

24.10.2016 | Life Sciences

Light-driven atomic rotations excite magnetic waves

24.10.2016 | Physics and Astronomy

More VideoLinks >>>