A team of scientists from Harvard Medical School and Boston's Children's Hospital have created models doen to the atom of key proteins that form part of the virus known as the rotavirus.

The rotavirus infects almost all children, usually between six months and two years old, and kills an estimated 440,000 children every year, mostly in poor countries.

The only licensed vaccine against rotavirus, called RotaShield, was pulled from the US market in 1999 over fears it could cause complications. It is made from live viruses.

Potent vaccine

But the American scientists, who published their findings in the British journal Nature, said a virus produced from the proteins they modeled could be more stable, cheaper and safer.

The proteins, located on parts of the virus - called the 'head' and 'body' - contain many of the targets that trigger an immune response to fight the disease, they said.

"The work is a clear example of the way in which structural studies can contribute to new good ideas about strategies for vaccines," senior investigator Stepehen Harrison said.

"A vaccine based on these proteins could be very practical, especially for developing countries where rotavirus causes the most serious illness," he added.