Scientists interested in doing experiments involving the H5N1 avian influenza virus and 14 other potentially dangerous biological agents face new requirements to get funding from the U.S. government. The new rules are a direct response to a global controversy that erupted in late 2011 after scientists created H5N1 viruses that some feared could spark a deadly human pandemic. Such changes please many, but some advocates for tougher biosecurity oversight aren't happy. Meanwhile, other researchers are resuming their H5N1 work now that a voluntary moratorium is over.