Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

First big influenza genome study reveals flu evolution

06.10.2005


Which flu did you get? TIGR scientists survey five New York flu seasons



On the eve of the 2005-06 flu season, scientists at The Institute for Genomic Research (TIGR) have captured influenza evolution in action. In a study published in this week’s journal Nature, the researchers report the first large-scale project to sequence the influenza virus. The study offers a unique snapshot of the rapidly evolving flu virus in a human population--and a new strategy for surveillance.

In the study, TIGR scientists and their colleagues sequenced 209 complete genomes of the human influenza A virus. The genomes represent virus samples, or isolates, taken from patients who visited county clinics across New York over the past five flu seasons, from 1999-2004. Almost all the influenza genomes represent the H3N2 strain, which predominated during these flu seasons. Comparing these genomes, the researchers tracked the changing virus as it moved across the region.


"This study demonstrates that genomics can help us better track the flu virus and develop more effective vaccines," remarks first author Elodie Ghedin, who heads TIGR’s viral genomics lab. "This is perhaps the most detailed snapshot scientists have gotten of flu’s movement through communities."

Across New York State, the researchers documented at least three distinct subpopulations (variants) of the H3N2 influenza virus over the five-year study period. In some of the flu seasons studied, these variants circulated simultaneously. That means New Yorkers weren’t all catching the same flu, but rather slightly different versions of the virus. Even within this relatively small geographic region, Ghedin says, the dynamic influenza virus showed striking diversity, with variants frequently swapping genetic material.

In fact, the researchers report, one such event explains why the 2003-04 flu vaccine offered less protection than usual.

Every flu season, a global network of scientists attempts to identify several predominant flu strains and factor them into the next season’s flu vaccine. Predictions are tricky, however, because influenza is constantly changing. In the 2002-03 flu season, the Nature study reports, a minor H3N2 variant reassorted, or genetically mixed, with the dominant strain. This reassortment yielded a new strain late in the season. The new strain quickly won out, becoming the dominant virus in the 2003-04 flu season. Because scientists had not factored this latecomer strain into the ’03-04 vaccine, however, the vaccine was less effective.

Genomics turns a new spotlight on influenza evolution. By deciphering the genomes of different influenza strains, researchers can pinpoint mutations that allow particular strains to become more virulent, adapt to infect new species, or evade immune response.

Moreover, TIGR’s high-throughput influenza genome sequencing pipeline offers a pivotal strategy for crafting emerging vaccines that work. "Right in the middle of flu season, we could determine which influenza strains are present in the population, which ones are dominant, and how well a given vaccine works," Ghedin notes. She adds that all sequences described in the current study have been deposited in public databases, such as GenBank, which allows immediate access to the scientific community.

The new study represents the initial results from the Influenza Genome Sequencing Project, launched in 2004 by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health. As part of this ongoing project, TIGR will sequence thousands of human flu isolates, as well as avian, equine, and swine flu isolates, to recognize influenza’s patterns of genetic change. To do so, TIGR has built an innovative viral genomics lab, which is ramping up to sequence 100 influenza genomes weekly.

Influenza poses a major public health problem. In an ordinary year, the flu kills up to a half million people worldwide. In the U.S., a typical flu season brings 36,000 deaths and 114,000 hospitalizations. Over the past century, three pandemics--in 1918, 1957, and 1968--caused millions of deaths. Today, scientists worry that virulent influenza strains in other species, such as the H5N1 bird flu strain found in poultry and migratory birds in Asia and Russia, will jump the species barrier into humans and trigger a new pandemic.

Although researchers first isolated the influenza virus in 1933, they still don’t fully understand how the virus evolves. Influenza is an RNA virus that contains eight separate RNA segments encoding genes for at least 11 proteins. This structure explains why the influenza virus constantly reassorts genetically. When two different influenza strains infect the same cell, their separate RNA segments can easily swap material, resulting in entirely new strains.

Type A influenzas (one of three major types, or genera) cause widespread flu among humans. Researchers classify type A influenzas according to structural variations in two surface proteins: hemagglutinin (HA) and neuraminidase (NA). Like changing coats, the influenza virus changes the shape of these HA or NA proteins when it accumulates minor mutations or reassorts more dramatically. The human immune system no longer recognizes the virus, and infection begins anew.

Steven Salzberg, senior author of the Nature paper, says the new work illustrates this chain of molecular events. "The study demonstrates that these influenza subpopulations, or variant strains, represent a pool of genetic resources that the influenza virus can draw upon," says Salzberg, a researcher at TIGR and also director of the University of Maryland’s Center for Bioinformatics and Computational Biology. "Pockets of distinct flu strains spread locally, with flu evolving in different directions. Then, when one strain mingles with another, a new, dominant strain can emerge."

Kathryn Brown | EurekAlert!
Further information:
http://www.tigr.org/

More articles from Life Sciences:

nachricht Climate Impact Research in Hannover: Small Plants against Large Waves
17.08.2018 | Leibniz Universität Hannover

nachricht First transcription atlas of all wheat genes expands prospects for research and cultivation
17.08.2018 | Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Smallest transistor worldwide switches current with a single atom in solid electrolyte

17.08.2018 | Physics and Astronomy

Robots as Tools and Partners in Rehabilitation

17.08.2018 | Information Technology

Climate Impact Research in Hannover: Small Plants against Large Waves

17.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>