Some scientists said the viruses might not only be accidentally released from the labs but potentially replicated by terrorists.

The moratorium ended last year. Kawaoka said he resumed his H5N1 research this May, after approval by federal officials.

The research on the 1918-like virus was done during the moratorium, which covered only the altered H5N1 virus work, Kawaoka said. UW-Madison approved the 1918-like virus research, and the National Institutes of Health reviewed the new report on the findings, university officials said.

Both projects were carried out at UW-Madison’s Institute for Influenza Virus Research at University Research Park on Madison’s West Side. The lab is classified as Biosafety Level 3-Agriculture, the highest biosafety level at the university and half a notch below the top level anywhere of BSL4.

In the new research, Kawaoka and his colleagues searched public databases of information on various flu viruses isolated from wild birds from 1990 to 2011. The researchers identified eight genes nearly identical to the genes that made up the 1918 pandemic flu virus.