US researchers said this week they have made progress toward an experimental vaccine against the deadly Ebola virus that is 80 percent effective in mice. Ebola is a rare but notorious African virus and feared future weapon of bioterrorism because it usually kills its victims by overwhelming the immune system, causing multiple organ failure and bleeding to death. Thirty-five years after Ebola first emerged, there is still no vaccine for human protection because none of the candidates were able to survive in long-term storage as part of a national stockpile to be kept in case of use in an attack. But scientists in Arizona reported in the Proceedings of the National Academy of Sciences on Monday that they have created a vaccine that fuses an antibody with tobacco plants, potentially yielding a more stable vaccine. They took part of a protein from the surface of the virus, melded it to an antibody that recognizes the viral protein and produced the vaccine in tobacco plants. The plant-derived immune complex was then injected into the mice along with another immune boosting chemical called PIC. Eight in 10 pre-treated mice survived a subsequent Ebola infection. All mice who did not receive the vaccine before being infected with Ebola died. More research is needed to determine if the vaccine would be safe and effective in people. According to the UN\'s World Health Organization (WHO), about 1,850 cases of Ebola, with some 1,200 deaths, have occurred since 1976. The virus has a natural reservoir in several species of the African fruit bat. Gorillas and other non-human primates are also susceptible to the disease.