Scientists have identified a chemical compound that can stop the H5N1 bird flu virus as well as seasonal human flu viruses from replicating.
Finding new flu drugs is essential as flu viruses mutate and are adept at evading the limited array of antiviral drugs.
In a paper published in Nature Biotechnology, scientists from Hong Kong and Canada said they had found a chemical "nucleozin", which fought off both seasonal flu viruses and the H5N1 in mice as well as in cell culture.
"We have now brand-new weapons to combat influenza virus resistant to ... (antiviral drugs like) oseltamivir and zanamivir," said microbiologist Richard Yao at the University of Hong Kong, who led the study.
Nearly all of the seasonal H1N1 viruses circulating in the United States in the 2008-2009 flu season were resistant to Roche AG and Gilead Sciences Inc's Tamiflu, known generically as oseltamivir, according to the paper.
Adamantanes, an older class of drugs, was also powerless against seasonal H3N2 flu viruses in the United States during that same period.
Zanamivir is the generic name for Relenza, GlaxoSmithKline and Biota Inc's flu drug
Nucleozin targetted a protein in flu viruses, called nucleoprotein, that was responsible for virus replication, Yao said in reply to questions from Reuters.
Yao said they selected nucleozin from a chemical library with more than 50,000 compounds, the same library which experts here used to study the SARS virus.
"Nucleozin is highly potent in cell culture and also in mice infected with the highly pathogenic influenza virus H5N1 ... (it can) stop the virus from replicating," Yao said.
The compound was effective against H1N1, H3N2, and H5N1 viruses and researchers can now target nucleoprotein to fight flu, Yao said.
"Scientists could now use nucleoprotein as a target to develop antiviral therapeutics for the treament of influenza infection," he said.
A cousin of the new H1N1 swine flu virus, the seasonal H1N1, has been circulating widely for a long time. SARS surfaced in southern China in 2003, killing about 800 people world-wide.
The H5N1, although mainly a disease in birds, has a mortality rate of 60 per cent on the rare occasions when it infects people. It was first discovered in people in 1997.