Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Flu viruses take one-way ticket out of Asia, then travel the world

18.04.2008
Study in Science may lead to improvements in flu vaccine design
Seasonal influenza strains constantly evolve in overlapping epidemics in Asia and sweep the rest of the world each year, an international research team has found.

These findings suggest that by focusing surveillance efforts on East and Southeast Asia, researchers may be able to extend their forecast of the flu strains most likely to cause epidemics, which may in turn help experts decide which strains should go in the flu vaccine each year.

The study, by a team of researchers from Europe, Australia, Japan and the United States, appears in the 18 April issue of the journal Science, which is published by AAAS, the nonprofit science society.

“The flu virus is constantly mutating, so it’s a major challenge for public health as well as a fascinating example of evolution in action. This study advances our knowledge of how new flu strains spread across the globe and how epidemics arise,” said Katrina Kelner, Science’s deputy managing editor, life sciences.

Colin Russell of the University of Cambridge in the United Kingdom and his colleagues analyzed 13,000 samples of influenza A (H3N2) virus, collected across six continents from 2002 to 2007 by the World Health Organization Global Influenza Surveillance Network. This subtype of influenza is currently the major cause of flu-related illness and death in humans.

The researchers compared physical differences in a surface protein, called hemagglutinin, across the different samples. Hemagglutinin is the primary target of the immune response, and even small changes can allow the virus to evade the immune system and cause disease.

In a subset of the samples, the researchers also compared the sequences of the gene that codes for hemagglutinin.

Together, these analyses allowed the researchers to identify different strains of A (H3N2) as they arrived at new locations around the world over the five-year period. The results revealed that strains emerge in East and Southeast Asia and then about six to nine months later reach Europe and North America. Several months later still, the strains arrive in South America. Essentially, once the strains leave East and Southeast Asia they enter an evolutionary graveyard.

“The ultimate goal of our collaboration is to increase our ability to predict the evolution of influenza viruses. This study is one step along that path and in particular highlights the importance of ongoing collaborations and surveillance in East and Southeast Asia, and of expanding these collaborations in the future,” said Derek Smith of the University of Cambridge, who is the corresponding author of the study.

Annual influenza epidemics are thought to result in 3 to 5 million cases of severe illness, and between 250,000 and 500,000 deaths every year, according to the World Health Organization (http://www.who.int/mediacentre/factsheets/fs211/en/index.html).

A (H3N2) is a subtype of the influenza A virus, and it is one of the three flu viruses included – in dead or in a weakened state – in the flu vaccine. The others are the influenza A (H1N1) subtype and the influenza B virus. Each year, the World Health Organization decides which strains within these three categories to include in the next vaccine, based on the recent activity of strains that are currently circulation.

The authors emphasized that the flu vaccine currently works extremely well, protecting about 300 million people from the disease each year, and that people should continue to be vaccinated annually. But, from time to time, a new strain begins infecting people after the vaccine has already been produced.

For decades, researchers haven’t known how influenza viruses migrate around the world. According to some of the scenarios that have been proposed, the viruses may migrate between the Northern and Southern hemispheres following the seasons, or they may have come out of the tropics where they were thought to circulate continuously, or they may have come out of China.

The Science study shows instead that each year since 2002, influenza A (H3N2) viruses have migrated out of what the authors call the “East and Southeast Asian circulation network,” and from there spread around the world.

Why Asia" For reasons that aren’t well-understood, flu epidemics break out during the rainy seasons in the tropics of East and Southeast Asia. On continents at higher latitudes, on the other hand, flu season simply occurs for a few months during the wintertime. Within Asia, different regions experience the rainy season at different times of year.

“Flu epidemics appear to be driven by seasonal factors such as winter, or rainy seasons. So there can be cities that are only 700 miles away from each other, such as Bangkok and Kuala Lumpur, which have epidemics six months apart. There is a lot of variability like this in East and Southeast Asia, so lots of opportunity for an epidemic in one country to seed an epidemic to another nearby country, like a baton passed by runners in a relay race,” Smith said.

“Our study is an example of the tremendous synergy between influenza science and public health,” he said. “The World Health Organization’s Global Influenza Surveillance Network tracks the evolution of influenza viruses for the primary purpose of influenza vaccine strain selection, but this also enables basic work on evolution.”

"The Global Circulation of Seasonal Influenza A (H3N2) Viruses," by C.A. Russell; T.C. Jones; A, Mosterin; E. Skepner; D.J. Smith at University of Cambridge in Cambridge, UK; T.C. Jones; J.C. de Jong; A.D.M.E. Osterhaus; G.F. Rimmelzwaan; R.A.M. Fouchier; D.J. Smith at Erasmus Medical Centre in Rotterdam, Netherlands; T.C. Jones; A. Mosterin at Universitat Pompeu Fabra in Barcelona, Spain; I.G. Barr; N.J. Cox; R.J. Garten; V. Gregory; I.D. Gust; A.W. Hampson; A.J. Hay; A.C. Hurt; A. Kelso; A.I. Klimov; T. Kageyama; N. Komadina; Y.P. Lin; M. Obuchi; T. Odagiri; M.W. Shaw; M. Tashiro at World Health Organization (WHO) Collaborating Centre for Reference and Research on Influenza in Melbourne, VIC, Australia; N.J. Cox; R.J. Garten; A.I. Kilmov; M.W. Shaw at Centers for Disease Control and Prevention in Atlanta, GA; V. Gregory; A.J. Hay; Y.P. Lin at National Institute for Medical Research in London, UK; T. Kageyama; M. Obuchi; T. Odagiri; M. Tashiro at National Institute for Infectious Diseases in Tokyo, Japan; A.S. Lapedes at Los Alamos National Laboratory in Los Alamos, NM; K. Stohr at Novartis Vaccines and Diagnostics in Boston, MA.

This study was funded by the National Institutes of Health Director’s Pioneer Award (http://nihroadmap.nih.gov/pioneer), the National Institute of Allergy and Infectious Diseases, the NWO Netherlands Influenza Vaccine Research Centre, the Australian Government Department of Health and Aging, and the Medical Research Council.

The American Association for the Advancement of Science (AAAS) is the world's largest general scientific society, and publisher of the journal Science (www.sciencemag.org). AAAS was founded in 1848, and serves 262 affiliated societies and academies of science, reaching 10 million individuals. Science has the largest paid circulation of any peer-reviewed general science journal in the world, with an estimated total readership of 1 million. The nonprofit AAAS (www.aaas.org) is open to all and fulfills its mission to "advance science and serve society" through initiatives in science policy; international programs; science education; and more. For the latest research news, log onto EurekAlert!, www.eurekalert.org, the premier science-news Web site, a service of AAAS.

Natasha Pinol | EurekAlert!
Further information:
http://www.aaas.org

More articles from Health and Medicine:

nachricht On track to heal leukaemia
18.01.2017 | Universitätsspital Bern

nachricht Penn vet research identifies new target for taming Ebola
12.01.2017 | University of Pennsylvania

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: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

A big nano boost for solar cells

18.01.2017 | Power and Electrical Engineering

Glass's off-kilter harmonies

18.01.2017 | Materials Sciences

Toward a 'smart' patch that automatically delivers insulin when needed

18.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>