A Dutch scientist performing U.S.-backed biodefense research was able to modify an avian flu strain into a more virulent version of the lethal virus, eliciting concerns that the findings could be misappropriated for acts of biological terrorism, Radio Netherlands Worldwide reported on Friday.

The U.S. National Institutes of Health requested that Rotterdam-based molecular virology professor Ron Fouchier examine whether the avian influenza virus H5N1 could cause a massive outbreak, according to the newspaper de Volkskrant. When the researcher sent a summary of his findings to Science for potential publication, the U.S. journal sought confirmation from the National Science Advisory Board for Biosecurity that the piece was safe to publish. The board is presently studying the matter.

Many specialists have responded with doubt about Fouchier’s findings from his investigation into avian flu, which was conducted under strict security protocols. The Dutch professor reportedly demonstrated that with a few changes to the genetic code, he was able to alter the virus into a highly contagious pathogen. Though typically fatal, the current avian flu is only infrequently transmitted from animals to people (Jacqueline Nolan, Radio Netherlands Worldwide, Nov. 25).