Avian Influenza Viruses May Have the Genetic Ingredients for a Pandemic: 1918-Like Outbreak

A certain virus may just have pandemic potential. Scientists have found that circulating avian influenza viruses contain all of the genetic ingredients necessary to underpin the emergence of a virus similar to the deadly 1918 influenza virus.

The 1918 virus, also known as the "Spanish flu" pandemic, was one of recorded history's most devastating outbreaks of the disease. In fact, it resulted in an estimated 40 million deaths worldwide. That's why it's crucial to understand its genetic underpinnings to prevent future pandemics.

In order to assess the risk posed by a virus that could acquire all eight of the 1918-like genes, the researchers employed revere genetics methods to create a virus that differed from the 1918 virus by only three percent of the amino acids that make up the virus proteins. The resulting virus was more pathogenic in mice and ferrets than an ordinary avian flu virus, but was not as pathogenic as the 1918 virus.

The scientists then conducted additional experiments to see how many changes it would take before the avian 1918-like virus to become transmissible in ferrets. In the end, the scientists identified seven mutations in three viral genes that would allow it to transmit efficiently.

The findings reveal a bit more about the mechanisms responsible for adaptation of avian influenza viruses to mammals. By understanding these mechanisms, the researchers can better treat an outbreak of a potential virus, warding against it.

"The point of this study was to assess the risk of avian viruses currently circulating in nature," said Yoshihiro Kawaoka, one of the researchers, in a news release. "We found genes in avian influenza viruses quite closely related to the 1918 virus and, to evaluate the pandemic potential should such a 1918-like avian virus emerge, identified changes that enabled it to transmit in ferrets...Eventually, we hope to be able to reliably identify viruses with significant pandemic potential so we can focus preparedness efforts appropriately."

The findings are published in the journal Cell Host & Microbe.