The flu virus can change the location of genes so quickly that it creates a defense front against the vaccines. This is how American researchers found out.
There are many strains of the flu virus
The evolution map of influenza viruses recently revealed the high frequency with which these viruses switch gene positions.
The results of the study raise concerns that a particularly persistent bird flu virus could mix genes from a human flu virus to start passing directly from person to person, creating a possible pandemic. The study also highlights the easiness of a strain of viruses for which we do not have a vaccine.
The scientists believed until now that the process of replacing the genes progresses slowly from season to season.
A team from the National Institutes of Medicine discovered instead that the influenza A virus replaced several genes at the same time, causing sudden changes in the virus.
The findings, published in the journal PLOS Biology, say that many strains can change each season, making it difficult to treat the disease.
Sudden mutations
Scientists have also raised concerns that the bird flu virus mutation is spreading rapidly among humans. Each year, the experts must identify which strains will be the most common and design a vaccine to combat them.
Dr. David Lipman and his colleagues examined the strains of influenza A that circulated in New York between 1999 and 2004. The studies confirmed the genetic diversity of the influenza virus and highlighted the potential for outbreaks of the disease.
These strains gave rise to the so-called Fujian strain H3N2 that caused outbreaks in the 2003-2004 flu season because the vaccine developed that winter was too weak to deal with the virus. Dr. Lipman's team found variation in the 156 strains analyzed. Some of the strains contained at least four gene exchanges that appeared in a very short period of time.
"The genetic diversity of the influenza A virus is not as limited as we previously thought." the researchers said. They suggest that scientists continue to study flu outbreaks more carefully due to the importance of mutations that occur suddenly without warning." said
The scientists are particularly concerned recently that the bird flu virus has developed a mutation and acquired the ability to spread from person to person other than through birds. "If this is indeed the case, it could kill millions around the world."
For news at the BBC
