Scientists believe they could slow the progress of "mad cow disease" by genetically "revamping" the brain.
CJD is caused by abnormal proteins
Tests in mice with scrapie - a disease similar to CJD in humans and BSE in cattle - showed the life-extending treatment works.
The method used by the German team involves molecules called special RNAs (siRNAs), Journal of Clinical Investigation reports.
These shut down the production of proteins that go awry in prion disease.
Prion proteins are very similar to healthy proteins, but have a slightly different shape.
When healthy proteins come into contact with the prions, they change their shape and become diseased as well.
This results in a chain reaction with more and more abnormal protein being deposited in the brain.
Professor Alexander Pfeifer and colleagues reasoned that shutting down healthy protein production using siRNAs would break the chain of events by depriving diseased prions of their ability to spread.
Special RNAs attach themselves to specific genes that hold the DNA code for proteins.
When the siRNA attaches, protein production shuts down - a process called RNA interference.
Professor Pfeifer's tested the theory in mice with scrapie, which is caused by an abnormal prion protein known as PrP-Scr.
They used siRNA to knock out virtually all of the healthy protein that PrP-Scr mutates.
While untreated diseased mice died after an average of 165 days, the mice treated with the siRNA lived much longer - for up to 230 days.
Professor Pfeifer, from the University of Bonn, said: "Basically, siRNAs seem to be a promising therapeutic option for scrapie, CJD or BSE."
But he added: "It will take years before the method can be used on human beings."
Dr Qingzhong Kong, an expert in prion diseases at the Case Western Reserve University in the US, said: "Much more research is needed before RNA interference can be harnessed to treat prion disease."
He said a big hurdle was getting the siRNA safely into the correct cells.
These treatments also carry the risk of upsetting the immune system and blocking non-target genes, he added.