New bird flu strain `adapting to mammals, humans`: Study
Washington: A genetic analysis of the avian flu virus responsible for at least nine human deaths in China portrays a virus evolving to adapt to human cells, raising concern about its potential to spark a new global flu pandemic, a study has said.
The group of researchers examined the genetic sequences of H7N9 isolates from four of the pathogen`s human victims as well as samples derived from birds and the environs of a Shanghai market.
"The human isolates, but not the avian and environmental ones, have a protein mutation that allows for efficient growth in human cells and that also allows them to grow at a temperature that corresponds to the upper respiratory tract of humans, which is lower than you find in birds," Yoshihiro Kawaoka, a leading expert on avian influenza, said.
Access to the genetic information in the viruses, he adds, is necessary for understanding how the virus is evolving and for developing a candidate vaccine to prevent infection.
Influenza virus depends on its ability to attach to and commandeer the living cells of its host to replicate and spread efficiently. Avian influenza rarely infects humans, but can sometimes adapt to people, posing a significant risk to human health.
Kawaoka explained that the majority of the viruses in the study, from both humans and birds, display mutations in the surface protein hemagglutinin, which the pathogen uses to bind to host cells.
Those mutations, according to Kawaoka, allowed them to easily infect human cells.
The collaborative study, conducted by a group led by Masato Tashiro of the Influenza Virus Research Center, National Institute of Infectious Diseases, and Yoshihiro Kawaoka of the University of Wisconsin-Madison and the University of Tokyo, will appear the journal Eurosurveillance.