Avian Flu Becoming More Resistant to Antiviral Drugs
Posted Jan 11 2009 2:53pm
Researchers using Google Earth technology are able to visually chart individual outbreaks of the avian flu as it has spread outward from China over the past decade, including gene mutations that are causing a resistance to a major class of antiviral drugs. A new University of Colorado at Boulder study shows the resistance of the avian flu virus to a major class of antiviral drugs is increasing through positive evolutionary selection, with researchers documenting the trend in more than 30 percent of the samples tested.
The avian flu, an Influenza A subtype dubbed H5N1, is evolving a resistance to a group of antiviral drugs known as adamantanes, one of two classes of antiviral drugs used to prevent and treat flu symptoms, said CU-Boulder doctoral student Andrew Hill, lead study author. The rise of resistance to adamantanes — which include the nonprescription drugs amantadine and rimantadane — appears to be linked to Chinese farmers adding the drugs to chicken feed as a flu preventative, according to a 2008 paper by researchers from China Agricultural University, said Hill.
In contrast, resistance of the avian flu virus to the second, newer class of antiviral drugs that includes oseltamivir — a prescription drug marketed under the brand name Tamiflu — is present, but is not yet prevalent or under positive genetic selection, said Hill of CU-Boulder’s ecology and evolutionary biology department. The CU findings should help health administrators around the world plan for the possibility of an avian flu pandemic.