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 A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht On the way to developing a new active ingredient against chronic infections
21.08.2017 | Deutsches Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Nagoya physicists resolve long-standing mystery of structure-less transition

21.08.2017 | Materials Sciences

Chronic stress induces fatal organ dysfunctions via a new neural circuit

21.08.2017 | Health and Medicine

Scientists from the MSU studied new liquid-crystalline photochrom

21.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>