Washington: Scientists have said that they have proof that descendants of the H2N2 avian influenza A virus that killed millions worldwide in the 1950s still pose a threat to human health, particularly to those under 50.
The study included 22 H2N2 avian viruses collected from domestic poultry and wild aquatic birds between 1961 and 2008, making it the most comprehensive analysis yet of avian H2N2 viruses.
Researchers reported the viruses could infect human respiratory cells.
Several strains also infected and spread among ferrets, which are susceptible to the same flu viruses as humans. Based on those and other indicators, one virus was classified as posing a high risk for triggering a pandemic.
Researchers found evidence the viruses were susceptible to current antiviral medications and could likely be controlled with an available prototype vaccine.
Such protection was unavailable in 1957 when an H2N2 virus that included genes from avian flu viruses emerged.
Corresponding author Robert Webster , Ph.D., a member of the St. Jude Department of Infectious Diseases, said that 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.
Along with being able to infect human trachea and other mammalian cells growing in the laboratory, five viruses also infected ferrets, according to researchers. Ferrets are a reliable model for studying flu's spread in humans. The five strains were among the nine H2N2 viruses that researchers tested in ferrets.
The research has been published online in the Journal of Virology.