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 scientist
Source:The Institute for Genomic Research