Bird-flu virus mutation discovered by Japanese and Vietnamese scientists

Bird-flu virus mutation discovered by Japanese and Vietnamese scientists

11:16' 09/10/2007 (GMT+7)

Source: VietNamNet Bridge

 

VietNamNet Bridge - Japanese and Vietnamese scientists have identified a mutation of an H5N1 avian flu virus that can grow in the human upper respiratory tracts. 

"Although effective human-to-human transmission of this virus has not yet occurred, the potential of the virus to acquire the ability is evident," said the researchers, who published their findings in the October issue of the U.S. journal PLoS Pathogens, which was released last week.  

The group of nine scientific researchers, led by professor Yoshihiro Kawaoka of the University of Tokyo, also found that the virus can spread by coughing and sneezing, signaling a potential for human-to-human transmission. 

"We believe another mutation may be necessary (for the virus) to cause a pandemic," Kawaoka said. "As more humans are infected, the greater the chance that the mutation will evolve." 

The researchers compared two H5N1-type viruses extracted from the throat and lung of a patient in Vietnam in 2004. They infected a mouse with the virus, and found it tended to grow in the upper respiratory tract, including the throat and nose, where flu viruses usually enter. 

Researchers also found that the temperature in these parts is about 33, lower than the average temperature of mammals, which is 37. This indicates that this particular mutation allows H5N1 to live in the human upper respiratory tracts that have cooler temperatures. Normally, bird flu does not grow well in the throat or nasal passages of humans. 

Kawaoka added that scientists need to closely monitor H5N1 avian flu viruses. 

Last year, Kawaoka and other scientists found another mutation, which allows the virus to infect people more easily, raising the expectation that these findings could help scientists to predict the emergence of new strains. 

(Source: Japan Times)