Australian researchers have identified immune cells which could fight all strains of influenza virus, a finding that raises hope for a universal vaccine which does not need to be updated annually.

The team from the Peter Doherty Institute for Infection and Immunity have identified immune cells called killer T cells that can fight all influenza viruses - A, B and C. It is a paradigm-shifting discovery, which could lead to the development of a world-first universal one-shot flu vaccine that does not need to be updated annually, the researchers said.

"Influenza viruses continuously mutate to evade recognition by our immune system, and they are vastly diverse, making it nearly impossible to predict and vaccinate against the strain that will cause the next influenza pandemic," said Marios Koutsakos from the Institute.

The study, published in the journal Nature Immunology, identified the parts of the virus that are shared across all flu strains as well as sub-strains that are capable of infecting humans. They also investigated "if we could find robust responses to those viral parts in healthy humans, and influenza-infected adults and children", Koutsakos said.

The team now has a patent on the discoveries, which will enable them to develop a universal influenza vaccine approach to reduce the impact of pandemic and seasonal influenza around the world. In addition to the experiments of the human immune system to prove the killer T cell commonality across all flu strains, something that has never been done before, the research team conducted vaccination tests to demonstrate the protective capacity of killer T cells. "Our immunisation studies with the peptide responsible for activating the killer T cells revealed remarkably reduced levels of flu virus and inflammation in the airways," Koutsakos said.