Dr. Fouchier’s work proved that H5N1 need not mix with a more contagious virus to become more contagious.

By contrast, the lead author of the other bird flu paper, Dr. Yoshihiro Kawaoka, of the University of Wisconsin-Madison, took the H5N1 spike gene and grafted it onto the 2009 H1N1 swine flu. One four-mutation strain of the mongrel virus he produced infected ferrets that breathed in droplets, but did not kill any.

The controversy erupted in December when the National Science Advisory Board for Biosecurity asked that details be removed before the papers were published. On March 30, it reversed itself after a similar panel convened by the World Health Organization recommended publication without censorship.

Dr. Kawaoka’s work was published by the journal Nature last month.

Dr. Fouchier had to delay until the Dutch government gave him permission, on April 27.

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.”

After the controversy erupted, he claimed the news media had overblown the danger.

Science magazine on Thursday published seven other articles about H5N1. One, by a team at Cambridge, concluded that it was not possible to accurately calculate the likelihood of all five mutations occurring in nature.

Up to three in a single human is “a possibility,” said Derek J. Smith, the lead author. “Five mutations is pretty difficult, but we don’t yet know how difficult it is,” Dr. Smith said.