Scientists say they have a vaccine that stops mice getting a brain disease similar to BSE in cattle and which may ultimately protect humans against vCJD.
Tight rules have been introduced to ensure that BSE-infected meat does not enter the UK food chain
Deadly prion diseases, like vCJD, are spread by consuming contaminated meat, and there is no cure or treatment.
A vaccine that decreases the spread of prion disease in animals would reduce the risk of spread in humans, says the New York University team.
It could also be considered for humans, they told a neurology meeting.
The diseases are caused by abnormal versions of prion proteins in the brain, which accumulate and cause brain damage, leading to dementia and abnormal limb movements.
As the infection takes hold, prion proteins invade brain tissue and force normal proteins to adopt their own misfolded shape.
Many research groups in the US and Europe are working on vaccines to block or avoid this process.
The prototype tested by Dr Thomas Wisniewski and his team was made from prion proteins attached to a genetically modified strain of a bug called Salmonella.
This bacterium is already used in a number of animal and human vaccines.
Many of the mice that received the oral vaccine had no symptoms of the disease after 400 days, while others had delayed disease onset.
Without the vaccine, it would normally take a mouse 120 days to develop the disease.
Dr Wisniewski said they were now in the process of redesigning the vaccine so it could be used on deer and cattle, and possibly humans, too.
He explained to the American Academy of Neurology: "If, for example, a more significant outbreak of chronic wasting disease in deer and elk occurs and if it were transmissible to humans, then we would need a vaccine like this to protect people in hunting areas.
"Or it could be given to delay disease in people with hereditary forms of prion disease or people who have been exposed to vCJD."
Professor David Brown, a prion disease expert at Bath University, UK, said: "These findings show that prion disease can be prevented and this is quite important.
"The major limitation of applying these findings to humans is that it remains impossible to tell who will develop CJD and who will not.
"If further work demonstrates that vaccination during early signs reverses symptoms, then it would be useable in treatment."