MADISON - By incorporating the slightest change in the arrangement of its molecules, the virus responsible for a brief but frightening influenza outbreak in Hong Kong several years ago can quickly morph from a relatively benign virus to a killer.
The discovery of the molecular basis for the extreme virulence of the virus known to scientists as Hong Kong H5N1 influenza A, was reported today, Sept. 7, in Science magazine, the nation's leading scientific journal. Using mice, a team of scientists from the University of Wisconsin-Madison showed that only minor molecular changes are required to turn a virus that, in its benign form, causes only minor respiratory illness to a potentially deadly virus that infects much of the body, including the heart and brain.
"Only a few changes make non-pathogenic viruses highly pathogenic," says Yoshihiro Kawaoka, a virologist at UW-Madison and corresponding author of the Science paper.
The virus responsible for the 1997 Hong Kong outbreak, which infected at least 18 people and killed six of those with known infections, is an avian flu virus and was transmitted to humans, most likely, in one or more of the bustling live poultry markets that dot Hong Kong.
Animals such as fowl and pigs are known reservoirs of influenza virus, and it is known that the major flu outbreaks - including the Asian and Hong Kong flu pandemics - occur when viruses leap from an animal host to humans.
At the time of the outbreak, a surveillance team found the virus in chickens, ducks, quail and geese. To stem the spread of the virus, the Hong Kong government ordered the destruction of all birds in Hong Kong's live poultry markets and an estimated 1.4 million birds were slaughtered.
Kawaoka says two unique things about the 1997 Hong Kong outbreak raise concern among virologists and public health officials: One was direct transmission of the virus from birds to humans, raising the specter that influenza outb
'"/>
Contact: Terry Devitt
trdevitt@facstaff.wisc.edu
608-262-8282
University of Wisconsin-Madison
6-Sep-2001