Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Plants provide accurate low-cost alternative for diagnosis of West Nile Virus

25.10.2012
While the United States has largely been spared the scourge of mosquito-borne diseases endemic to the developing world—including yellow fever, malaria and dengue fever—mosquito-related illnesses in the US are on the rise. One pathogen of increasing concern in the U.S. is an arbovirus known as West Nile.

Now Qiang “Shawn” Chen, a researcher at Arizona State University’s Biodesign Institute and a professor in the College of Technology and Innovation has developed a new method of testing for West Nile, using plants to produce biological reagents for detection and diagnosis.

The new research, conducted by Chen and his colleagues at the Center for Infectious Diseases and Vaccinology recently appeared in the Journal of Biomedicine and Biotechnology.

“One critical issue in WNV diagnosis concerns the difficulty of distinguishing WNV infection from other closely related diseases, such as St. Louis encephalitis and dengue fever, due to the cross-reactivity of antibodies among flaviviruses,” Chen says. “It is important to develop better diagnostic tools with enhanced accuracy for both treatment and diagnostic purposes.”

Thus far, the 2012 outbreak of West Nile in the United States is on track to be one of the worst on record. According to the Center for Disease Control, 48 states have reported West Nile virus infections in people, birds, or mosquitoes as of October 9th of this year.

To date, 4,249 cases of West Nile virus disease have been reported in humans, including 168 deaths. Of these cases 2,123 (50 percent) appeared in the more severe or neuroinvasive form of the disease, causing meningitis and encephalitis, while 2,126 cases were classified as non-neuroinvasive.

These figures represent the highest number of West Nile cases reported to the CDC since 2003, with nearly 70 percent reported from eight states: Texas, California, Louisiana, Mississippi, South Dakota, Michigan, Oklahoma, and Illinois. Over a third of total cases have been reported from Texas.

The alarming upswing in West Nile cases coupled with their broad geographic distribution demand new techniques for both diagnosis and treatment. Chen and his colleagues have been exploiting the power of plant biotechnology to achieve these goals.

Earlier, Chen’s group developed the first successful plant-derived therapeutic to combat West Nile post-infection, reporting their results in the Proceedings of the National Academy of Science. The current study advances efforts to create a diagnostic test for West Nile that will overcome barriers of existing methods, including limited accuracy, prohibitive cost and scalability.

In nearly all cases, West Nile is transmitted to humans through the bite of an infected mosquito. Mosquitoes acquire the virus after feeding on infected birds. The virus then migrates to the mosquito's salivary glands, from which it may be injected into humans and animals. There, it can multiply and produce characteristic symptoms of West Nile disease. These may present as flu-like malaise including fever and chills, headaches, fatigue and pain in muscles and joints. Symptoms typically last three to six days, but may persist for weeks.

In around 1 in 150 WNV cases, individuals develop infections of the brain (encephalitis) or surrounding tissue (meningitis), often producing severe headache, fever, stiffness, confusion, convulsions, coma, tremors, muscle weakness and paralysis. Those with neurologic involvement may require weeks of hospitalization and may suffer permanent health effects including muscle weakness and paralysis. Around 10 percent of people with WNV encephalitis die.

Faced with the growing threat of mosquito-borne epidemics, researchers like Chen stress the necessity of developing rapid, low-cost platforms for diagnosis of West Nile. Traditionally, cell cultures from serum, cerebrospinal fluid or tissues have been examined but the short viremic phase and low viral count of WNV in blood and spinal fluid limit the sensitivity and accuracy of such tests. Protein-based methods like ELISA have become standard tests for West Nile, yielding better results but at considerably higher cost and with limited scalability.

In the current study, plants were exploited for their ability to produce large volumes of proteins that can be used for diagnostic testing. As Chen explains, proteins produced in this way traditionally require a lengthy time period before transgenic plant lines can be established. By contrast, the new method, which makes use of plant viral-based vectors like Tobacco Mozaic Virus and Gemini Virus, relies on the ability of plants to transiently express particular target genes, yielding the desired protein in 1-2 weeks.

The technique provides the speed and flexibility of a bacterial gene expression system while permitting the posttranslational modifications of proteins afforded by mammalian cell culture approaches.

Chen’s group used plant transient expression systems to produce two varieties of protein reagents useful for the detection and diagnosis of WNV—one a recombinant antigen and one a monoclonal antibody. High expression levels of both reagents were observed in two kinds of plants: Nicotiana benthamiana (a close relative of tobacco) and lettuce. The two reagents may be readily purified to greater than 95 percent and retain their native functionality and specificity.

The production of plant-derived antigens and monoclonal antibodies offers an attractive alternative to the use of mammalian, insect or bacterial cell cultures and demonstrates the capability of plants to provide accurate and flexible diagnostic reagents not only for WNV but a broad range of arboviruses affecting human health.

“Our test will improve the accuracy of diagnosis, leading to the proper treatment of patients affected by WNV,” Chen says. “The plant-derived monoclonal antibody we examined is not only low-cost, but highly specific for WNV antigen and does not recognize antigens from other flaviviruses.” Chen further notes that application of this research will ultimately allow a broad range of WNV surveillance capabilities, from clinical diagnosis to global distribution patterns in wild bird and mosquito populations.

Click to read the study
http://www.hindawi.com/journals/jbb/2012/106783/

Richard.Harth | EurekAlert!
Further information:
http://www.asu.edu
http://www.biodesign.asu.edu/news/plants-provide-accurate-low-cost-alternative-for-diagnosis-of-west-nile-virus

More articles from Life Sciences:

nachricht The dense vessel network regulates formation of thrombocytes in the bone marrow
25.07.2017 | Rudolf-Virchow-Zentrum für Experimentelle Biomedizin der Universität Würzburg

nachricht Fungi that evolved to eat wood offer new biomass conversion tool
25.07.2017 | University of Massachusetts at Amherst

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA mission surfs through waves in space to understand space weather

25.07.2017 | Physics and Astronomy

Strength of tectonic plates may explain shape of the Tibetan Plateau, study finds

25.07.2017 | Earth Sciences

The dense vessel network regulates formation of thrombocytes in the bone marrow

25.07.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>