The vaccine against Alzheimer's disease has come a step closer to reality since scientists have succeeded in preventing the increase in toxic brain proteins associated with this disease.
Mouse experiments have shown that the DNA vaccine injected into the skin can potentially delay the onset of Alzheimer's disease without serious side effects.
Scientists say the findings, published in the Alzheimer's Research and Therapy Magazine, could pave the way for clinical trials in human patients.
It is believed that two types of toxic proteins or protein building blocks play a key role in Alzheimer's, beta-amyloid and tau.
The beta-amyloid accumulates in adhesive clumps in the brain and is a characteristic feature of the disease seen in post-mortem examination of patients.
Tau is a protein that produces destructive "freezers" in nerve cells. Some studies suggest that both are related, with a beta-amyloid that promotes the formation of tau tangles.
The new vaccine contains DNA coding for a segment of the blockade of beta-amyloid protein or peptide.
In the study, the vaccine caused an immune response, which not only led to a 40% reduction in beta-amyloid structure, but also reduced the formation of tau by 50%.
The research was conducted on mice that were genetically engineered to develop a glacial equivalent of Alzheimer's disease.
The main obstacle to developing effective Alzheimer's vaccines is to find safe ways to get introduced into the body.
A previous experimental vaccine developed in the early 2000s caused brain swelling in some patients when tested for humans.
The new vaccine is injected into the skin, rather than the muscles, which leads to a different kind of immune response.
If repeated in humans, the effects observed in mice will have "great therapeutic value", say the researchers.
"If the onset of the disease can be postponed for as long as five years, it will be paramount for patients and their families," said co-author of the study, Dr Doris Lambracht-Washington.
"The number of cases of dementia can be reduced by half," she said.