Shares in US biotechnology firm Viragen went through the roof on Friday after it reported that its lead product was effective in combating the avian influenza virus.

Viragen said that its Multiferon (multi-subtype, human natural alpha interferon) product was more effective against the H5N1 strain of avian flu, widely tipped as the most likely strain to cause a pandemic – than recombinant alpha interferon, recombinant beta interferon or ribavirin.

Although the data was from an in vitro assessment and Multiferon is still a long way from being a treatment option for pandemic strains of flu, Viragen’s shares rose by more than 20% to close at

Viragen said it believes the drug, sold in 10 markets outside the USA for infectious diseases and cancer, may have utility against the virus, and that it is worthy of further evaluation.

It added that the data obtained from these studies will be added to a patent application filed with the UK Patent Office in February 2004 covering the use of natural, multi-subtype alpha interferon for human treatment and prevention of avian influenza virus.