Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Flu tracked to viral reservoir in tropics

18.04.2008
Each winter, strains of influenza A virus infect North Americans, causing an average of 36,000 deaths. Now, researchers say the virus comes from a viral reservoir somewhere in the tropics, settling a key debate on the source of each season's infection.

"We now know where the influenza A virus comes from every year," said Edward Holmes, professor of biology at Penn State. "And because we now know how the virus evolves, we have a much better chance of controlling it."

Currently, there are many strains of the influenza virus that appear only in birds, which are natural viral reservoirs. So far three of these viral strains -- H1N1, H2N2 and H3N2 – have caused epidemics in humans as influenza A.

Of the three, H3N2 is the dominant strain, responsible for most influenza infections each winter, with lower levels of H1N1. However, little is known about how these two strains spread on a geographical scale, and how whole genome of influenza A virus evolves.

Holmes and his colleagues analyzed complete genomes of 1,032 strains of H1N1 and H3N2 viruses sampled over a 12-year period from New York state in the northern hemisphere and New Zealand in the southern hemisphere.

The researchers noticed that over time, both strains follow a distinctive pattern. In seasons where the H3N2 strain is dominant, H1N1 is not and vice versa.

"We found that the two strains peak at different times, and seem to be directly competing with each other" said Holmes, whose findings appear today online in Nature. The results also indicate that compared to the H3N2 strain, the H1N1 strain exhibits far less genetic diversity, although it is not clear why.

Holmes says his results also show that the influenza A virus is frequently exchanging genes by reassortment – when multiple human influenza viruses infect a single person and shuffle their genes – which sometimes allows the virus to acquire a new haemagglutinin, a protein that facilitates the entry of viral particles into the host cells.

These new haemagglutinins sometimes cause vaccines to fail, explained Holmes, whose work is funded by the National Institutes of Health.

"The critical thing is unless you understand the way the genome evolves, you will not understand why vaccines work during some years and fail during others," he added. "We can now show that vaccines failed in some years because new haemagglutinins appeared."

The Penn State researcher says his analysis not only indicates how the influenza virus is evolving, but also where new strains are being generated.

Each year new strains appear in the northern hemisphere, infect people and then burn out. However, patterns of genetic diversity within the viruses suggest the strains are coming from a global source population. The researchers believe that there must be some reservoir somewhere that every year generates new strains that are injected each season into the north and the south, and then burn themselves out.

"We know the strains are dying out every year in the northern and southern hemispheres. So they're surviving somewhere else, and we think it is a reservoir in the tropics," Holmes said. "It tells us that to really understand how the influenza virus evolves on a seasonal basis, and to make the best vaccine, we need to focus our surveillance on the source population in the tropics, especially in places such as Southeast Asia."

Amitabh Avasthi | EurekAlert!
Further information:
http://www.psu.edu

More articles from Health and Medicine:

nachricht Serious children’s infections also spreading in Switzerland
26.07.2017 | Universitätsspital Bern

nachricht New vaccine production could improve flu shot accuracy
25.07.2017 | Duke University

All articles from Health and Medicine >>>

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

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

26.07.2017 | 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

 
Latest News

CCNY physicists master unexplored electron property

26.07.2017 | Physics and Astronomy

Molecular microscopy illuminates molecular motor motion

26.07.2017 | Life Sciences

Large-Mouthed Fish Was Top Predator After Mass Extinction

26.07.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>