Widely effective preventative: 3-D illustration of the influenza virus.
Credit: iStockphoto
Similar vaccination studies on attacking the inside of the virus body rather than its surface are also under way abroad, including at Oxford University in Britain, Uchida said.
About 250 people have died of avian flu since 2003, according to the WHO. Indonesia is the country worst-hit by avian influenza with 115 deaths officially recorded since 2003.
Five deaths have been reported in China this month, compared with just three in the whole of 2008, alarming health officials.
China is considered one of the nations most at risk of bird flu epidemics because it has the world's biggest poultry population and many chickens in rural areas are kept close to humans.
Human victims consist mostly of people in close contact with sick birds. There is no evidence so far that the deadly strain of bird flu has mutated into a form that could set off a pandemic.
