Chinese researchers have discovered mutations in the new strain of avian influenza A, known as H7N9, and have found that the virus has the ability to spread from human to human, the latest issue of the Guangzhou-based Southern Metropolis Weekly reported. George F Gao, vice president of the Beijing Institutes of Life Sciences under the Chinese Academy of Sciences and deputy director-general of the Chinese Center for Disease Control and Prevention, told the Weekly that he and his research colleagues have broken down the mechanisms of transmission of the H5N1 and H7N9 avian flu viruses. The research team pointed out in a study published in the Science magazine in September last year that they have identified mutations in four key sites of amino acids of the H7N9 strain and found that the virus has an ability to bind to human cells in the upper respiratory tract.
Although the H7N9 and H5N1 viruses have not had the ability to widely spread from human to human, after undergoing genetic mutations and redistribution through mutations, they become better able to bind to human cells in the upper respiratory tract and can evolve into bird flu strains with the ability to transmit among humans, the team says. In nature, H7N9 is an avian flu virus, but it tends to bind to poultry cells in the lower respiratory tract, Gao said. He added that although the H7N9 virus can invade cells in the human upper respiratory tract, it only has a limited ability to transmit among humans. This winter, China reported several human cases of H7N9 bird flu, with two new cases reported Friday in eastern China’s Zhejiang province and one death in southern China’s Fujian province. The report said that H5N1 and H7N9 have been two of the the most lethal avian influenza viruses for humans in recent years. Since the first case of human influenza A H5N1 was reported in 1997 in Hong Kong, the virus has affected more than 60 countries around the world, with a fatality rate of 60%. More