Melbourne scientists have discovered what they say is a chink in the armour of the flu virus that could prevent a repeat of the devastating 1918 influenza pandemic.

The breakthrough could lead to the development of a new arsenal of "smart" flu vaccines within 10 years.

Up to 40 million people died from the 1918 outbreak, in which a savage mutant flu virus swept around the world in three months - spreading faster and claiming more lives than any plague in history.

If a new mutation unleashed a similar pandemic today, current vaccines - which are only effective against certain flu strains - would be useless.

But a team from Melbourne University, working with US colleagues from St Jude children's Research Hospital in Memphis, say they have paved the way for the development of a new class of vaccine that could be used against even the most rogue of mutant viruses.

The discovery is based on new findings about the mechanism behind the body's T-cell response to the flu virus.

Existing flu vaccines are based on antibody, rather than a T-cell activity, by priming antibodies to target proteins that cling to the surface of the virus.

However, these proteins can undergo sudden and radical changes, resulting in resistance to vaccines and potential pandemics.

On the other hand, T-cells give the immune system a boost by recognising certain non-mutating proteins inside the flu virus.

Steve Turner of the University of Melbourne's department of immunology and microbiology said a T-cell-based vaccine was likely to remain effective over a longer time because of the stability of the proteins targeted.

"We can now genetically modify the flu virus that we're interested in to examine and dissect out the T-Cell responses," he said.

"It's a genetic way of basically making designer flus - the idea is if you identify a potential dangerous strain, you can actually modify that to generate a vaccine and prepare stockpiles of it in the event of an outbreak."

The research is published in the journal Proceedings of the National Academy of Sciences.

©AAP 2003