Scientists have successfully immunised mice against the deadly Ebola virus which has killed thousands in Africa.
Ebola kills most victims
They used virus-like particles (VLPs) which are non-infectious but are capable of triggering a strong response by the immune system.
Usually lethal doses of Ebola had no impact on the vaccinated mice.
The study, by the US Army Medical Research Institute of Infectious Diseases, is published in Proceedings of the National Academy of Sciences.
The scientists hope their work will lead to a vaccine which will protect humans from the virus, which causes haemorrhagic fever and kills up to 90% of its victims.
Not only is it one of the world's most lethal diseases, terrorism experts fear it could be used as a biological weapon.
Currently there are no available vaccines or therapies.
The researchers created VLPs from two Ebola virus proteins. These VLPs resemble the outer covering of infectious viral particles, but lack the genetic material necessary to reproduce themselves.
Mice were vaccinated with VLPs three times at three-week intervals and exposed to the Ebola virus six weeks after the last vaccination.
The result was 100% protection with no signs of illness in the immunized mice.
VLPs have already been tested and found efficacious as vaccines for several other viruses, including HIV.
The next stage will be to test the vaccine in primates.
Lead researcher Dr Steve Bavari said: "The beauty of this approach is that VLPs are not a traditional vaccine platform, so you don't have to worry about the recipient building up immunity to that platform.
"It looks like a virus, so you have the protective immune response, but it's basically an empty shell."
The researchers also believe VLPs could be used to develop new tests to identify Ebola-infected samples.
Colonel Erik Henchal, commander of USAMRIID, said: "This is astonishing work.
"The ability to produce self-assembling particles that resemble whole virus will give us a new tool to evaluate the combination of variables required to produce a protective immune response to Ebola virus."