MOSCOW, July 11 (RIA Novosti) - The H7N9 avian flu, responsible for dozens of deaths in China, has a potential to mutate into a strain that can easily pass from human to human, sparking a global pandemic, an international team of scientists said.
The H7N9 strain infected 132 people in China, killing 43 of them as of July 10, according to a Xinhua statement quoting Chinese health authorities. A team of scientists of the University of Wisconsin-Madison and the University of Tokyo has thoroughly analyzed samples of the virus and published their findings in the Nature magazine on Wednesday.
"H7N9 viruses have several features typically associated with human influenza viruses and therefore possess pandemic potential and need to be monitored closely," Yoshihiro Kawaoka, one of the world's leading experts on avian flu who headed the team, was quoted as saying by the Science Daily.
The group found out that the virus is able to infect and replicate in several species of mammals, whose immune system is close to human, such as ferrets and monkeys. The study suggests that the ability of the H7N9 virus to infect and replicate in human cells may be due to just a few amino acid changes in the genetic sequence of the virus.
They also established that approximately one third of ferrets became infected by droplet spread.
"H7N9 viruses combine several features of pandemic influenza viruses, that is their ability to bind to and replicate in human cells and the ability to transmit via respiratory droplets," he said. "These two features are necessary, although not sufficient, to cause a pandemic."
In monkeys, the virus could efficiently infect cells in both the upper and lower respiratory tract. Conventional human flu viruses are typically restricted to the upper airway of infected nonhuman primates.
"If H7N9 viruses acquire the ability to transmit efficiently from person to person, a worldwide outbreak is almost certain since humans lack protective immune responses to these types of viruses," Kawaoka said.
However, the study found that the H7N9 strains showed certain sensitivity to antiviral drugs effective against the conventional seasonal flu virus.
