A strain of avian flu related to the 1950s pandemic that killed millions of people worldwide still pose a threat to human health.
From a recent study, St. Jude Children's Research Hospital scientists have evidence that descendants of the H2N2 avian influenza A virus is dangerous to those under 50.
Researchers examined 22 H2N2 viruses collected from domestic poultry and wild aquatic birds between 1961 and 2008, "making it the most comprehensive analysis yet of avian H2N2 viruses," according to a press release.
"This study suggests H2N2 has the characteristics necessary to re-emerge as a significant threat to human health in part because most individuals under the age of 50 lack immunity to the virus," corresponding author Robert Webster, Ph.D., a member of the St. Jude Department of Infectious Diseases, said in a statement. "This highlights the importance of continued surveillance of viruses circulating in animals and additional research to enhance our ability to identify viruses that are emerging health threats."
Researchers discovered the viruses could infect human cells and spread among ferrets, which are susceptible to the same flu viruses as humans. According to researchers, based on those and other indicators, one virus was classified as posing a high risk for triggering a pandemic.
According to researchers, based on those and other indicators, one virus was classified as posing a high risk for triggering a pandemic.
In a press release, study author Jeremy Jones noted that while the viruses genetically look avian, the study shows they can also behave like human viruses and replicate multiple models of the mammalian flu.
"That is troubling because some of the original H2N2 pandemic viruses looked avian when the pandemic began in 1957, but in a few short months, all of the isolated viruses had picked up the genetic signatures of adaptation to humans," Jones said in a statement. "Our results suggest the same could happen if the H2N2 viruses again crossed from birds into humans."
However, researchers found evidence the viruses were susceptible to current antiviral medications and could likely be controlled with an available prototype vaccine - protection that was not available in 1957 when an H2N2 virus that included genes from avian flu viruses emerged.
Federal health officials estimate the 1957-58 pandemic killed 1 to 2 million people worldwide. While the H2N2 strain disappeared from flu viruses circulating in humans in 1968, it's persisted in the world's bird population.
Jones said work is underway at St. Jude to identify other changes that are critical to the ability of avian flu viruses to infect and replicate in mammalian cells.
