Science News - June 2, 2012

Turkey 12 cases 4 deaths

Azerbaijan 8 cases 5 deaths

Pakistan 3 cases 1 death

Egypt 167 cases 60 deaths

Iraq 3 cases 2 deaths

Bangladesh 6 cases 0 deaths

Nigeria 1 case 1 death

Djibouti
Myanmar
Thailand
25 cases
17 deaths

1 case 0 deaths

Human bird flu

following an outbreak in 1997, more than 600 people worldwide are known to have been infected with h5n1 bird flu (darker red shows countries with cases this year). More than half have died as a result of the infection. souRce: woRld health oRganization

ridiculed for our position on the risks of
the influenza virus,” Osterholm says. If
smallpox or SARS were ever to escape
from a lab and start infecting people, it
would be bad but could easily be brought
under control, he says. “Influenza is very
different. Influenza is like having one
screen door on your submarine. It will
sink you.”
So telling the general public, includ-
ing potential terrorists, how to make an
airborne version of highly lethal H5N1
was, at least at first, deemed a risk that
outweighed the public health benefit of
publication.

But other scientists were outraged by the decision, which they saw as holding back essential information. The papers show that although H5N1 has been around for 15 years and has not yet developed the ability to spread easily from person to person, it could be just a few mutations away from becoming a human-transmissible virus. Full disclosure about the steps required for that transformation could be key to finding viruses already heading down that path in the wild.

The Netherlands group, headed by Ron Fouchier of Erasmus Medical Center in Rotterdam, found that five

mutations are enough to make the virus infectious through airborne particles in ferrets, which are often used as stand-ins for humans in infectious disease experiments. At the Royal Society meeting, Fouchier was unable to discuss details about the type of mutations that his group found because of Dutch restrictions on the export of dual-use research. (Fouchier’s team has since been granted an export license.)

But the United States had already lifted a similar ban, giving Yoshihiro Kawaoka of the University of Wisconsin–Madison the go-ahead to present his team’s results in full. Kawaoka’s team also reported its findings online May 2 in Nature.

Strictly speaking, the Wisconsin group’s transmissible virus is not H5N1 bird flu virus. Instead it is a composite of H5N1 and the H1N1 “swine flu” virus that caused a pandemic in 2009. To create the combination virus, the researchers replaced a sugar-spiked protein called hemagglutinin (the H in H5N1) found in the 2009 virus with one from the bird flu virus. Hemagglutinin studs the flu virus’s outer envelope and helps the virus grab and invade cells. Although the researchers genetically engineered

Lao People’s
Democratic Republic
2 cases
2 deaths

China 41 cases 28 deaths

Indonesia 189 cases 157 deaths

Hong Kong 21 cases 7 deaths

Vietnam 123 cases 61 deaths

Cambodia 20 cases 18 deaths

the bird/swine combination virus in the lab, the experiment mimicked the sort of parts-swapping that influenza viruses often go through in nature.

Merely swapping hemagglutinins wasn’t enough to make the composite virus into an airborne infectious flu in ferrets, though. The original combination virus didn’t pass between ferrets in neighboring cages. Researchers helped the virus along by transferring it directly from one ferret to another. In ensuing rounds of researcher-assisted ferret infections, mutations cropped up in the hemagglutinin protein.

At least four changes to the molecule were needed to make the virus readily transmit via airborne droplets, the researchers found. Three of the mutations, all located in a part of the protein needed to attach to cells, switched the virus from one that could latch onto cells in the digestive tract of birds and the lungs of mammals to one that also could hang on in mammalian upper respiratory tracts. Grabbing on in that region is necessary for virus particles to spread via coughing and sneezing.