Researchers have made use of computational techniques and mathematical methods to identify 6 influenza viruses that has close genetic connections to swine flu virus.
Biological studies focused on these strains of influenza virus said that five of these viruses were isolated from pigs, while the sixth had infected a human who worked with hogs.
The researchers found these strains by using powerful computers to analyse the relationships between the genomes of more than 5,000 strains of influenza A that have been isolated over several decades and recently sequenced.
"It's not unlike a social network, except that it's tracking an exchange of genetic material rather than gossip," Daniel Janies, associate professor of biomedical informatics at Ohio State University and a co-author of the study, said.
"This network gives us an explicit historical and molecular map of how influenza A viruses evolved from several ancestors to modern-day viruses," he said.
Janies jointly with Ohio State co-authors Shahid Bokhari, a research professor of biomedical informatics, and Laura Pomeroy, a postdoctoral researcher in veterinary preventive medicine, obtained data on all fully sequenced influenza A viruses available in a National Institutes of Health database.
They then used supercomputers to efficiently track how all of these influenza A viruses are related to each other and which paths through the network led to pandemic H1N1 of 2009.
The research was published online in the journal IEEE Transactions on Computational Biology and Bioinformatics.