Scientists identify six influenza A viruses related to H1N1 pandemic

Using new mathematical and computational techniques, scientists have identified six influenza A viruses with close genetic relationships to the H1N1 swine flu virus that created a pandemic in the U.S. in the spring of 2009.

The H1N1 virus eventually killed close to 18,000 people worldwide. The biological studies that are focused on these influenza virus strains might reveal how the 2009 pandemic strain emerged, which could aid researchers in efforts to forestall another pandemic, according to

Five of the viruses were isolated from pigs and the sixth had infected a human who worked with hogs. The researchers used powerful computers to analyze the relationships between the genomes of over 5,000 strains of influenza A that had been isolated over several decades. The network captured paths leading from previously observed viruses to contemporary viruses.

Biologists usually use a tree to trace how viruses change over time, but viruses also exchange genetic material with contemporaries, most commonly when two or more strains infect the same host, in a process called reassortment. This computer-based networking model is a novel way to see how the changes happened in influenza over time.

"It's not unlike a social network, except that it's tracking an exchange of genetic material rather than gossip," Daniel Janies, an associate professor of biomedical informatics at Ohio State University and a co-author of the study, said, reports. "This network gives us an explicit historical and molecular map of how influenza A viruses evolved from several ancestors to modern-day viruses."

The scientists obtained data from all 5,016 viruses that were fully sequenced in the National Institutes of Health database as of Oct. 15, 2009. They then used supercomputers to create a database outlining the differences and similarities in the genomes of all the strains. This allowed them to determine which paths through the network of viruses led to the pandemic H1N1 of 2009.

"These viruses just popped out at us," Shahid Bokhari, a co-author and research professor of biomedical informatics, said, according to "We found that 3,600 out of almost 4,000 paths to pandemic H1N1 were passing through these six bottlenecks. That threw up a red flag and said there is something unusual about these six. These bottlenecks are the culprits just a few steps removed from the virus that caused the pandemic among humans. Biologists are encouraged to look at these viruses to determine what underlies the emergence of animal diseases in humans.”

The researchers hope to use this model to study how bacteria can become resistant to antibiotics or become very pathogenic over time.

"Bacteria will exchange genetic material, and that material is often something that encodes toxins or genes for resistance to a specific antibiotic. The same approach will be used in that context to find out where bacteria, such as those that recently emerged in Europe, pick up these changes," Janies said, reports.

Organizations in this story

National Institutes of Health 9000 Rockville Pike Bethesda, MD - 20892

Get notified the next time we write about National Institutes of Health!