# 3482
Since 2005, the dominant theory has been that the 1918 pandemic virus – an H1N1 virus – made the direct leap from birds to humans and caused the worst pandemic in recorded history.
Today, a new study published in PNAS (Proceedings of the National Academy of Sciences) calls into question that theory, and promotes the idea that the 1918 virus, along with other pandemic viruses of the last century, circulated widely in humans and pigs – probably for years - picking up a series of genetic changes before turning into a pandemic strain.
Dating the emergence of pandemic influenza viruses
Gavin J. D. Smith, Justin Bahl, Dhanasekaran Vijaykrishna, Jinxia Zhang, Leo L. M. Poon, Honglin Chen, Robert G. Webster, J. S. Malik Peiris, and Yi Guan
PNAS published online before print July 13, 2009, doi:10.1073/pnas.0904991106
The pedigree of this research is pretty impressive, with such familiar names as Robert Webster, Guan Yi, and Malik Peiris involved.
While probably not the last word on this subject, their research points out the need for enhancing our surveillance of flu viruses, including looking at their internal genes.
By tracking changes, we may be able to predict more accurately when a pandemic virus is about to emerge. Follow the link to read the article in its entirety.
Experts unearth history of pandemic flu viruses
Mon Jul 13, 2009 5:00pm EDT
By Tan Ee Lyn
HONG KONG, July 14 (Reuters) - Flu viruses that sparked the three worst pandemics in the last century circulated in their near-complete forms for years before the catastrophes occurred, researchers in Hong Kong and the United States have found.
The H1N1 virus that sparked the Spanish flu of 1918-1919 circulated in swine and humans well before the pandemic started, and it did not come directly from birds as previously thought, they added. Instead, it was probably generated by genetic exchanges between flu viruses from swine and humans.
This contrasts sharply with previous studies which suggested that the H1N1 virus of 1918 was a mutant that jumped direct from birds to human and ended up killing as many as 50 million people.
The findings are considered important because of the lack of studies of the virus in animals before the current outbreak of H1N1. Through understanding the natural history of viruses, monitoring of current viruses can be fine-tuned, the team from the University of Hong Kong and St Jude Children's Hospital in the United States wrote.
