…six months after a scientific advisory board suggested that the papers’ most potentially dangerous data be censored.
The paper, by scientists at Erasmus Medical Center in the Netherlands, identified five mutations apparently necessary to make the bird flu virus spread easily among ferrets, which catch the same flus that humans do.
Two of the five mutations are already common in the H5N1 virus in the wild, said Ron A. M. Fouchier, the paper’s lead author. One has been found in H5N1 only once. The remaining two have never been found in wild H5N1, but occurred in the H2 and H3 flus that caused the 1957 Asian flu pandemic and the 1968 Hong Kong flu.
The Dutch team artificially introduced three mutations. The last two occurred as the virus was “passaged” through 10 generations of ferrets by using nasal washes from one to infect the next. Four changes were in the hemagglutinin “spike” that attaches the virus to cells. The last was in the PB2 protein. As the virus became more contagious, it lost lethality. It did not kill the ferrets that caught it through airborne transmission, but it did kill when high doses were squirted into the animals’ nostrils.
Dr. Fouchier’s work proved that H5N1 need not mix with a more contagious virus to become more contagious.
Some of the early alarm was fed by Dr. Fouchier speaking at conferences and giving interviews last fall in which he boasted that he had “done something really, really stupid” and had “mutated the hell out of H5N1” to create something that was “very, very bad news.” He said his team had created “probably one of the most dangerous viruses you can make.”