Researchers have developed a vaccine combining genes from four strains of influenza which may provide lifelong protection and soon pave the way toward a universal flu shot.

In a first-ever study, published in Scientific Reports, the researchers looked whether a universal flu shot could be created by using a combination of multiple genes shared at the ancestral level by flu strains circulating today.The researchers from the University of Nebraska-Lincoln in the US, reported the use of multiple centralised hemagglutinin (HA) genes, identified using protein sequence analysis programmes, to provide the greatest level of cross-protective immunity possible."Our idea is that these centralised antigens can set up a foundation of immunity against influenza," said lead researcher Eric Weaver, Assistant Professor at the University of Nebraska-Lincoln in the US.

"Because they are centralised and represent all the strains equally, they could provide a basis for immunity against all evolved strains," he added.The unconventional new vaccine was administered onto mice that survived exposure to lethal doses of seven of nine widely divergent influenza viruses. Those that received higher doses of the vaccine did not even get sick.On the other hand, mice that received traditional flu shots or nasal sprays all sickened and died when exposed to the same viruses. 

The deadly pathogens were able to evade the immune responses triggered by the traditional vaccines.While it is too soon to say the approach could be successfully used in humans, it appears to be a promising avenue toward a universal flu shot, Weaver said."The ultimate goal is to be able to vaccinate once and provide lifelong protection," Weaver added.However, it could take until 2020 or 2025 before a universal flu vaccine is available, the experts rued.The approach is "scalable and translatable to humans and may provide the foundation for complete and long-lasting anti-influenza immunity", Weaver said.