Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Identifying tick genes could halt disease, bioterrorism threat

03.09.2004


engorged deer tick, sits fingertip of Catherine Hill


female tick, engorged with blood


Ticks as small as a freckle can transmit a number of illnesses for which there is no vaccine and, in some cases, no cure. These creatures even could become bioterrorism weapons.

To find new ways to control the tiny animals and halt the spread of the pathogens they carry, Purdue University researchers and colleagues from the University of Connecticut Health Center, the University of Notre Dame and Massachusetts Institute of Technology are undertaking the job of unraveling the genetic makeup of one variety of the creature, called the deer or black-legged tick. "This will be the first time researchers have explored a tick genome in depth," said Purdue’s Catherine Hill, project co-principal investigator. "It’s crucial to learn how ticks spread serious illnesses because of the global health threats these diseases pose. "From a bioterrorism standpoint, it’s pretty clear ticks could transmit a number of diseases that intentionally could be introduced and conveyed to people."

The scientists involved in this project have formed the International Ixodes scapularis Sequencing Committee. One of the potential outcomes of this project may be development of vaccines to block transmission of microbes that cause tick-borne illnesses, said Hill, who spearheaded efforts to gain National Institutes of Health backing for the initial stages of the tick genome venture.



Hill and her Purdue researchers are preparing materials that will be the foundation of the sequencing project, she said. She already has begun extracting RNA from ticks at different stages of their lifecycle and from different tissues in the tick. These samples will provide the scientists with the first clues as to the types of genes present in ticks and how gene expression changes when ticks are infected with disease-causing microorganisms. "Once we begin to collect the genome data, we will analyze what the genes do and how they control tick behavior, including how they are able to spread disease," she said.

Stephen Wikel is co-principal investigator on the project, which is funded by the NIH’s National Institute of Allergy and Infectious Diseases. "The tick genome project will extend our search for molecules that are essential for ticks to feed and transmit pathogens," said Wikel, director of the Center for Microbial Pathogenesis at the University of Connecticut Health Center.

The collaborators will delve into how ticks find animals to feed on, feeding methods, blood meal digestion, development of disease-causing microbes within the tick, tick reproduction, transmission of infectious agents, new control methods and evolutionary biology.

Bruce Birren and his team at The Broad Institute at MIT will do the initial sequencing of the deer tick genome. The sequence data will be used to identify tick genes. When this step is complete, the multi-institutional research team and other scientists throughout the world will use the genome data to search for ways to halt tick-borne illnesses.

An invertebrate creature known as an arthropod, ticks transmit, or vector, more pathogens to humans and other animals than any other blood-feeding organism. Indeed, experts now believe one tick type in the United States transmits West Nile virus, previously believed to be only mosquito-borne in this country. Hill and her colleagues selected the deer tick, scientifically known as Ixodes scapularis, in part because of its large impact on human and animal health.

Deer ticks are the main vectors for Lyme disease, which is the most commonly reported tick-transmitted human disease in the United States. Lyme disease can cause lethargy, joint swelling and facial paralysis. Some of the symptoms can become chronic arthritis and neurological syndromes. In 2002 the Centers for Disease Control and Prevention recorded approximately 24,000 cases of the often-misdiagnosed and under-diagnosed illness. This was a 40 percent increase over the previous year.

A number of ticks in the United States spread pathogens that the CDC considers potential bioterrorism weapons. The family to which I. scapularis belongs, Ixodidae, carries many of the microbes included on the CDC’s Select Biological Agents and Toxins list. Among the diseases caused worldwide by these organisms are Rocky Mountain spotted fever, tularemia, Crimean-Congo hemorrhagic fever and tick-borne encephalitic diseases.

Ticks spread disease by taking blood from an infected animal and then feasting on another animal. They need the blood to grow from egg to adult, and the adult female needs the blood to nourish her eggs.

In the case of Lyme disease-carrying deer ticks, the larvae feed on infected white-footed mice and other small mammals that harbor the pathogens. The tick develops into a nymph, which carries the Lyme disease-producing bacteria to people, pets and other animal species.

The tick’s olfactory system, or what we call our noses, is in its feet. These organs recognize carbon dioxide, which animals, including people, emit when they exhale. Ticks lie in wait until they receive the carbon dioxide signal that a meal is nearby. Then they leap, sink their mouths into flesh, and gorge themselves while at the same time spreading insidious diseases.

Ticks feed on a diverse group of hosts including people, pets, livestock, reptiles and birds. Most of these are susceptible to the pathogens carried by one type of tick or another. Ticks have unique ways of interacting with both host and the disease-causing microbes they carry, Hill said. A host is the animal from which the tick sucks blood.

"Ticks stay on their host for a long time, and they’ve developed a complicated mechanism to avoid being detected," said Hill, an entomology assistant professor. "Ticks can increase the blood supply to the area where they’re feeding. They release pain inhibitors so the host can’t tell that they are present and a whole host of complicated proteins that prevent the host immune response from getting rid of them."

Currently very little is known about the tick genome, which is about two-thirds the size of the human genome, Hill said. Many animals and plants have similar genes with similar functions, but ticks have some unique genes different even from other invertebrates.

With a better understanding of the deer tick, researchers hope to learn much about the whole branch of the evolutionary tree that includes this arthropod, she said. "This is an exciting opportunity to study this unique organism in a new way," Hill said. "We will be able to identify targets for development of novel insecticides to control ticks and new vaccines to control the pathogens they carry."

Other members of the team are Frank Collins, University of Notre Dame biology professor, and Vishvanath Nene, of TIGR - The Institute for Genomic Research - in Rockville, Md.

Susan A. Steeves | EurekAlert!
Further information:
http://www.purdue.edu

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

DGIST develops 20 times faster biosensor

24.04.2017 | Physics and Astronomy

Nanoimprinted hyperlens array: Paving the way for practical super-resolution imaging

24.04.2017 | Materials Sciences

Atomic-level motion may drive bacteria's ability to evade immune system defenses

24.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>