US group BioCryst saw its shares surge more than 17% to close at $22.41 yesterday after a bout of frenzied trading, as investors revelled in the news that the group’s antiviral peramivir has been accepted by US regulators for a speedy review, signalling a potential decision by May this year.

Peramivir was filed with the US Food an Drug Administration (FDA) in November 2004 for the treatment of flu infections, but investor excitement was largely ignited by the fact that, in preclinical trials, the agent was effective against the more dangerous strains including the notorious H5N1, which causes bird flu.

If a pandemic of bird flu occurs, an event that many experts believe is imminent, the potential for an effective antiviral is huge. If approved, peramivir will be competing against Roche’s Tamiflu (oseltamivir) and GlaxoSmithKline's inhaled Relenza (zanamivir). But there is growing concern that the virus is developing resistance to Tamiflu, the current gold standard of treatment, as some patients with bird flu have not responded to treatment with the drug. If this is the case, then the need for new antivirals is more desperate than ever.