Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Earlier bites by uninfected mosquitoes boost West Nile deaths in lab mice

20.11.2007
There’s one more reason to try to avoid being bitten by mosquitoes, scientists have discovered: bites from mosquitoes that aren’t infected by the West Nile virus may make the disease worse in people who acquire it later from West Nile-infected mosquitoes.

Researchers from the University of Texas Medical Branch at Galveston (UTMB) announced their discovery in a paper published online by the journal PLoS ONE. In the paper, they describe experiments showing that lab mice on which mosquitoes have previously fed are far more likely to die from West Nile infection than are mice unexposed to such mosquito bites.

The effect is induced by mosquito saliva, according to UTMB professor Stephen Higgs, one of the paper’s senior authors.

“This virus is transmitted from mosquitoes in saliva, and we’d already demonstrated that mosquito saliva has an effect on the vertebrate immune system that makes West Nile infection worse,” Higgs said. “What this new work shows is that the saliva delivered by even earlier feedings can also alter the course of the infection. This is important, because in natural situations in many parts of the world – Southeast Texas, for example — animals and some people are being exposed to mosquito feeding almost continuously.”

... more about:
»Feeding »Higgs »UTMB »West Nile virus »immune »saliva »uninfected

In their experiments, researchers exposed sedated mice to feeding by between 15 and 20 Aedes aegypti mosquitoes for an hour once a week. Scientists then allowed a single West Nile virus-infected mosquito to feed once on each of these mice and also on each of a control group of mice that were previously unbitten by mosquitoes.

The results were striking: 68 percent of mice exposed to two weekly mosquito feedings died of West Nile virus, and those exposed to four weekly mosquito feedings suffered a 91 percent mortality rate. By contrast, the virus killed only 27 percent of the mice previously unexposed to saliva from mosquitoes that were free of West Nile infection. Analyses of responses of the mouse immune systems also showed a strong contrast between the previously exposed and unexposed mice.

“When we examined the immune reactions, one that stood out was an increase in the immune signaling molecule interleukin-10,” said Brad Schneider, the paper’s lead author and a UTMB alumnus who is now a postdoctoral fellow at the Institut Pasteur in Paris. “This host response to the saliva of the mosquito causes a shift in the immune response at the site where the virus first contacts the host, and the virus takes advantage of this shift.”

The UTMB researchers were surprised to find that mosquito bites seemed to have a detrimental effect with West Nile virus, because multiple earlier bites from other uninfected arthropods can actually protect against the parasites and bacteria carried by them. “Previous work has clearly indicated that pre-exposure to the bites of uninfected sand flies has a protective effect for mice against cutaneous leishmaniasis,” said Dr. Lynn Soong, the paper’s other senior author and an immunologist who works on the sand fly-transmitted protozoan parasite infection, dubbed “Baghdad boil” by American troops in the Middle East.

“Since this goes against the work we’ve seen with both bacteria and parasites, we definitely didn’t expect this result,” Schneider said. “But when we stood back and looked at it, it made sense. For a parasite or bacterium, the influx of immune cells brought in by this inflammatory response would be negative, but with the West Nile virus, you’re just giving it more susceptible cells to infect.”

Both Higgs and Schneider emphasized that the mouse experiments offered no definitive answers to the question of human responses to West Nile. “This is a mouse model, but that’s the best we’ve got at the moment,” Higgs said. “The thing is, it suggests that there may be yet another reason to avoid mosquitoes, to tidy up your yard and wear mosquito repellant.”

Jim Kelly | EurekAlert!
Further information:
http://www.utmb.edu
http://www.plosone.org/article/fetchArticle.action?articleURI=info:doi/10.1371/journal.pone.0001171

Further reports about: Feeding Higgs UTMB West Nile virus immune saliva uninfected

More articles from Life Sciences:

nachricht Show me your leaves - Health check for urban trees
12.12.2017 | Gesellschaft für Ökologie e.V.

nachricht Liver Cancer: Lipid Synthesis Promotes Tumor Formation
12.12.2017 | 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: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Long-lived storage of a photonic qubit for worldwide teleportation

12.12.2017 | Physics and Astronomy

Multi-year submarine-canyon study challenges textbook theories about turbidity currents

12.12.2017 | Earth Sciences

Electromagnetic water cloak eliminates drag and wake

12.12.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>