Novel Neuraminidase Inhibitor Shows Promise against H5N1 Avian Influenza Virus

Drug developers have shown that the novel antiviral neuraminidase inhibitor R-125489 administered as its prodrug CS-8958 works effectively against the highly pathogenic influenza A virus H5N1 (the avian influenza virus), including oseltamivir (Tamiflu)-resistant strains.

An international team of virologists and infectious disease experts from as far a field as the University of Wisconsin (Madison, USA) and the University of Kobe (Japan) reported in the February 26, 2010, online edition of the journal PLoS Pathogens that a single dose of CS-8958 given to mice two hours after infection with H5N1 influenza viruses produced a higher survival rate than did continuous five-day administration of oseltamivir.

Virus titers in lungs and brain were substantially lower in infected mice treated with a single dose of CS-8958 than in those treated with the five-day course of oseltamivir. Furthermore, a single dose of CS-8958 given seven days prior to virus exposure also protected mice against H5N1 virus lethal infection.

At the molecular level, the investigators found that R-125489 bound to the viral neuraminidase more tightly than did any other neuraminidase inhibitor tested. Summing up, the authors wrote that, "Our results indicate that CS-8958 is highly effective for the treatment and prophylaxis of infection with H5N1 influenza viruses, including oseltamivir-resistant mutants.”

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University of Wisconsin
University of Kobe