Lawrence LeBlond for redOrbit.com Your Universe Online

The new bird flu strain that has so far killed 11 people in China has been showing signs that it is quickly adapting to mammalian (particularly human) hosts, according to a new study led by Masato Tashiro of the Influenza Virus Research Center at the National Institute of Infectious Diseases (NIID) in Japan, along with Yoshiro Kawaoka of the University of Wisconsin-Madison (UWMadison) and the University of Tokyo.

Despite the growing fears that humans are readily being affected by this new strain, with at least 40 confirmed cases of sickness, the researchers maintain that it is still too early to predict potential for a global pandemic. The research was published April 11 in the journal Eurosurveillance.

The findings were drawn from genetic analysis of the new H7N9 virus strain. Samples of the strain had been deposited into an international database by Chinese researchers hoping to get a grip on the virus early. The research results are significant, as the first cases were seen less than three weeks ago the first human cases were reported on March 31 by the US Centers for Disease Control and Prevention (CDC).

The research group examined the genetic sequences of H7N9 isolates from four human victims as well as samples from birds and environs of the Shanghai market where the birds were being sold.

Study coauthor Kawaoka, an avian influenza expert, said: 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.

When the research news broke four days ago, human cases were at 33 illnesses with nine deaths. Todays figures confirm that cases are growing steadily, but still do not facilitate fears that a pandemic is in the making. Kawaoka said, however, that gaining access to the genetic information in the virus will help researchers understand how the virus is evolving and allowing for the development of a vaccine to prevent further infection.

Influenza depends on its ability to attach and take control of living cells in order to replicate and spread effectively. Avian bird flu rarely infects humans, but can pose a significant health risk if and when it does adapt.

These viruses possess several characteristic features of mammalian influenza viruses, which likely contribute to their ability to infect humans and raise concerns regarding their pandemic potential, Kawaoka and his colleagues said in the report.

The majority of the viruses the researchers examined in the study those that derived from both human and birds have been found to display mutations in the surface protein hemagglutinin, which the virus uses to bind to host cells. Kawaoka explained that those mutations allowed the pathogen to easily adapt to infect human cells.

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Genetic Analysis Of H7N9 Bird Flu Strain Reveals Easy Adaptation To Humans

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