The anti-HIV drugs known as protease inhibitors may be effective against the bird flu virus, according to an Italian researcher.

　　The H5N1 strain of avian flu has devastated poultry flocks in southeast Asia and caused the deaths of 47 people. It is considered a global health threat, because it could mutate into a strain that is easily passed from person to person, people have no immunity to it, and a vaccine would take months to produce.

　　Evidence that protease inhibitors may be of use against H5N1 is indirect, suggested by findings that these agents are effective against a third virus, the severe acute respiratory syndrome (SARS) virus, which has structural similarities to H5N1.

　　In a paper to be published in the Journal of Clinical Virology, Dr. Andrea Savarino of the Catholic University of the Sacred Heart, Rome, discusses how the anti-HIV drug Kaletra -- a combination of two protease inhibitors, ritonavir and lopinavir -- showed potential benefit in treating patients with SARS.

　　This was surprising, since the SARS virus does not produce a protease enzyme resembling that found in HIV.

　　However, Savarino told Reuters Health, computer simulations showed that protease inhibitors did bind to the main SARS protease, dubbed 3CL-pro, and that the sequence of the 3CL-pro was similar to a component of H5N1's protease.

　　"The message I would like to give to the world," he concluded, "is that there is enough evidence to begin testing HIV protease inhibitors against the deadly H5N1 virus."