Chinese scientists say H7N9 bird flu virus can be efficiently spread through droplets

On July 18th, Chinese scientists reported in the online edition of the American "Science" magazine that their most comprehensive and systematic study of the H7N9 bird flu virus so far has found that it may "spread efficiently" through droplets. The researchers said that this means that the global need to strengthen the preparation for prevention and control.

From the end of March to the beginning of May this year, researchers from the National Avian Influenza Reference Laboratory of Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences collected from poultry markets, poultry farms, wild bird habitats and slaughterhouses in Shanghai, Anhui, and Zhejiang. More than 10,000 samples were tested and more than 50 H7N9 strains were confirmed. To understand the genetic relationship between them, the researchers performed genome sequencing of the representative 37 H7N9 strains and compared them with 5 H7N9 strains isolated from humans.

The study found that these H7N9 strains are particularly similar, with only a few tens of amino acid differences, but their biological characteristics are quite different. However, all human and avian virus strains can bind to human respiratory receptors, and some virus strains also maintain their ability to bind to respiratory receptors in birds.

The researchers used five ferrets similar to those of humans to conduct transmission experiments of five H7N9 strains. Two of the virus strains were from chickens and pigeons, and the other three strains were from the earliest three human infections in Shanghai and Anhui. Cases. They found that in addition to virus strains from chickens, the remaining 4 virus strains can be transmitted through the respiratory droplets, and the transmission efficiency of the virus from Anhui is the highest.

Combining with the results of genome sequencing, Chen Hualan, director of the National Avian Flu Reference Laboratory, told Xinhua News Agency reporters: “This shows that the H7N9 strain may require only a few amino acid mutations and will become the same as the H7N9 strain from Anhui patients. Effective spread among animals."