University-led research revealed a strain of the avian flu virus once considered less severe could develop the ability to be transmitted from one mammal to another, leading to a human pandemic, according to results published by the Public Library of Science.
A team that included researchers from Associate Professor Daniel Perez’s lab in the university’s veterinary medicine department used ferrets to find some H9N2 avian viruses pose a significant threat to humans.
The study revealed the viruses can infect and transmit between mammals, said Erin Sorrell, a third-year doctoral student and one of 18 people who contributed to the study.
The research was done over the past year predominantly by Sorrell and Hongquan Wan, a former university postdoctoral worker now at the Centers for Disease Control and Prevention, and was funded by grants from the Centers for Disease Control and Prevention, National Institute of Allergy and Infectious Diseases and United States Department of Agriculture.
H9N2 avian viruses have been found in poultry in many Eurasian countries and “have caused repeated human infections in Asia since 1998,” the report reads.
The H9N2 strain is less dangerous than the often-deadly H5N1 strain, according to the World Health Organization. But there have been no reports of H5N1 transmitting from human to human, Sorrell said.
In the study, five types of H9N2 viruses isolated from different infected birds from 1988 through 2003 were found to replicate in ferrets. Two of those viruses transmitted to ferrets in direct contact with one another but did not transmit through air, according to the results published online Aug. 13.
The scientists also revealed how replication and efficient transmission of the viruses occur. A particular amino acid, for instance, was found to be important for transmission of the H9N2 viruses in ferrets.
Previous studies of H9N2 have used animals such as chickens, quail and mice, but “none of these models truly reflect the transmission of influenza in humans,” according to the story. Ferrets are the best model for human influenza studies, Sorrell said.
“Something that could infect us will be able to infect a ferret,” Sorrell said.
According to the report, H9N2 viruses “still lack a key component necessary for efficient aerosol transmission among mammals and, perhaps, humans.” But other studies have shown the “viruses are undergoing extensive evolution and reassortment, fueling their pandemic potential.”
Scientists still have a lot to learn in terms of what it takes for a virus to transmit from human to human, Sorrell said.
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