Japanese researchers said Monday they had paved the way to develop an all-round vaccine to protect people from bird flu and its feared mutations.
The new method entails injecting into the body a tiny bit of fat, known as a liposome, which is carrying an antigen on its surface.
Current vaccines on bird flu rely on the immune system's ability to attack the virus itself but they become ineffective if the virus mutates.
The new method "targets the inside of the virus, rather than its surface," as the inside of the virus structure rarely changes, said Tetsuya Uchida, researcher at the National Institute of Infectious Diseases.
"It would stop the virus from replicating itself," he told AFP. "There is the possibility that this may lead to a vaccine that could work against multiple flu viruses."
More than 200 people have died and poultry flocks have been devastated since the avian influenza broke out in 2003.
Human victims consist mostly of people in close contact with sick birds. But the World Health Organisation warns that a mutation of the bird flu virus could lead to a pandemic killing millions worldwide.
The Japanese researchers have conducted tests on mice which found that the method was effective on different strains of the bird flu virus.
The team aims to start tests using mice planted with human genes from April, Uchida said, adding it would be years until their research is put to practical use as a flu vaccine.
The study is being jointly conducted by researchers from the national institute, Hokkaido University, Saitama Medical University and NOF Corp., a leading chemicals company based in Tokyo.