New H5N1 Antiviral and Vaccine

Researchers testing a new neuraminidase inhibitor for prevention and treatment of H5N1 influenza infection reported promising findings in a mouse study today, suggesting that the new antiviral may be effective even against oseltamivir (Tamiflu)-resistant strains. The international study group, headed by Dr Yoshihiro Kawaoka, is based at the University of Wisconsin in Madison, and their findings appear in Public Library of Science (PLoS) Pathogens. Previous animal studies of the neuraminidase inhibitor R-125489 and its prodrug CS-8958 have shown that the drug is effective against seasonal flu. In the new study, the group found that mice that were given a single intranasal dose of CS-8958 2 hours after experimental H5N1 infection had higher survival rates and lower virus levels than those given a standard 5-day course of oseltamivir. Also, mice that were given a single dose 7 days before infection with the virus were protected. The researchers also found that R-125489 bound more tightly to neuraminidase than any of the other drugs they tested.

In similar news, Hungarian and British researchers, writing in the February Journal of Virology, report that a single-dose, adjuvanted H5N1 influenza vaccine generated a good immune response in adult and elderly volunteers. In the trial, 480 people were randomly assigned to receive one or two 3.5-microgram (mcg) doses of the vaccine or one dose of 6 or 12 mcg. Single doses of 6 mcg or more triggered antibody responses that met European Union and US licensing criteria for flu vaccines, the report says. No unexpected adverse events were reported. "We found that the present vaccine is safe and immunogenic in healthy adult and elderly volunteers and requires low doses and, unlike any other H5N1 vaccines, only one injection to trigger immune responses which comply with licensing criteria," the report states. The vaccine, made by Omninvest of Hungary, contains an aluminum phosphate adjuvant.

This news comes as Vietnam announces it's third reported case in 2010 of human H5N1.

Source: CIDRAP News http://www.cidrap.umn.edu/cidrap/content/influenza/avianflu/news/feb2610scan.html