Deadly flu virus flourishes in lung cells

A strain of bird flu that has sickened 132 people and killed 37 in China this year may have more potential to spread worldwide than the dreaded H5N1 avian influenza does.

The new flu, known as H7N9 avian influenza, latches onto sugars that coat bird cells — and it can cling to sugars on human cells too, Yuelong Shu of the China Center for Disease Control and Prevention and colleagues report July 3 in Nature. That may give the virus the ability to jump from birds to people relatively easily, the team reports.

By contrast, outside of two highly publicized laboratory experiments (SN: 6/2/12, p. 20), the H5N1 virus only grasps onto bird sugars and hasn’t developed the ability to be readily transmitted among people. H5N1 has infected 630 people worldwide, killing 375.

H7N9 grows especially well in lung cells, the team discovered. That finding helps explain why people infected with H7N9 often develop severe pneumonia. But the virus doesn’t cling as well in the trachea, which could limit H7N9’s ability to spread among people via coughs or sneezes.

The researchers also examined blood samples from 90 healthy people who had gotten flu shots in 2012 and 2013. None of them carried antibodies that can fight H7N9, indicating that most people are probably susceptible to the virus.