Doctors are hoping that swine flu could hold the key to the creation of a universal vaccine to protect against different variations of influenza.
Experts in the United States are questioning whether the 'Holy Grail' of flu vaccine research can be realised after some patients infected with last year's swine flu pandemic developed broadly protective immune system antibodies.
A single jab that provides long-lasting protection against a wide range of flu viruses could alleviate some of the problems experienced in Britain recently, as supplies of the seasonal vaccine began to run out.
Study leader Dr Jens Wrammert, from Emory University in Atlanta, Georgia, said: "Our data shows that infection with the 2009 pandemic influenza strain could induce broadly protective antibodies that are only rarely seen after seasonal flu infections or flu shots.
"These findings show that these types of antibodies can be induced in humans, if the immune system has the right stimulation, and suggest that a pan-influenza vaccine might be feasible."
Dr Wrammert's research team examined nine patients aged between 21 and 45 who became infected with swine flu last winter.
The severity of their cases ranged from enduring mild sickness for a few days to others who suffered severe symptoms and required a two-month stay in hospital.
Genes isolated from white blood cells taken from the patients were used to produce an assortment of 86 antibodies in the laboratory.
Antibodies are customised immune system agents, made by certain white blood cells, which target potentially harmful molecules or "antigens" carried by invading bacteria and viruses.
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