New York, Dec 22 (IANS): A vaccine that researchers developed to fight a fatal brain disorder in animals also holds promise for similar brain infections among humans.

The study marks a scientific milestone as it is the successful vaccination of deer against chronic wasting disease (CWD), a fatal brain disorder caused by unusual infectious proteins known as prions that propagate by converting otherwise healthy proteins into a disease state.

According to researchers, this vaccine may also work against human brain diseases suspected to be caused by prion infections, such as Creutzfeldt-Jakob disease, kuru, familial insomnia, and even Alzheimer's disease.

"Now that we have found that preventing prion infection is possible in animals, it is likely feasible in humans as well," said senior study investigator and neurologist Thomas Wisniewski, a professor at New York University Langone Medical Center .

For the study, five deer were given the vaccine and another six were given a placebo.

The animals receiving the vaccine were given eight boosters over 11 months until key immune antibodies were detectable in blood, saliva, and faeces.

Within two years, all of the deer who were given the placebo developed chronic wasting disease. Four deer, who were given the real vaccine, took significantly longer to develop infection and the fifth one continues to remain infection free.

The researchers made the vaccine using Salmonella bacteria, which easily enters the gut, to mirror the most common mode of natural infection -- ingestion of prion-contaminated food or faeces.

To prepare the vaccine, the team inserted a prion-like protein into the genome of an attenuated, or no longer dangerous, Salmonella bacterium. This engineered the Salmonella to induce an immune response in the gut, producing anti-prion antibodies.

The study appeared online in the journal Vaccine.