Ebola: finally an effective treatment

The hemorrhagic fevers caused by Ebola and Marburg are often fatal. A new study suggests hope for the development of a treatment, which has already been proven in monkeys but whose trials are pending.

Ebola is one name that sends shivers down your back. Worthy of a horror movie, this virus causes a hemorrhagic fever in most cases fatal for the patient who is bleeding to death. This disease occurs only in Africa, where outbreaks can cause death of 90% of those infected. The Ebola virus is transmitted first great ape to man and man to man very easily by aerosol or by contact. Bats could correspond to the reservoir of the virus since some people showed virions without being affected by the disease. Since 1976 and the discovery of Ebola virus, 1,850 cases were reported in dozens of outbreaks and more than 1,200 cases have been fatal. For now, there is no way to heal.

Attempts of vaccine against the Ebola virus have yielded interesting results in recent years but none of them is currently on the market. The research is rather slow because the laboratories working on the Ebola virus must demonstrate a high level of security, P4. They are therefore very limited. In Europe, only laboratory Jean Merieux in Lyon, has obtained such authorization.

Nevertheless, the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), in collaboration with the private laboratory AVI BioPharma, have developed a new therapy that appears to be effective against the Ebola virus itself and against his cousin, the Marburg virus. This treatment uses phosphorodiamidate antisense morpholino oligomers (PMO). These molecules resemble the barbarous name short fragments of DNA but are slightly modified to be more resistant to degradation and to penetrate easily inside cells.

By binding specifically with complementary sequence on a region of DNA or RNA, the nucleic acid PMO makes inaccessible to replication enzymes or gene expression. Theoretically, the virus unable to replicate, or bad, the immune system has enough time to put on and remove the virus before it has time to do damage.

The macaque crab, used in medical research, is susceptible to infection by Ebola and Marburg. Credits DR

Up to 100% survival

To determine the molecule PMO most effective, surveys were first conducted on mice and guinea pigs. With the PMO AVI-6002, over 90% of animals have had a favorable outcome of the disease, they have been exposed to the disease before or after treatment. These results have led researchers to test the treatment on rhesus monkeys. The treatment, administered 30-60 minutes after exposure to the virus, has saved the lives of five of eight monkeys. With an optimal dose of 40 milligrams per kilogram, the following experiments have allowed the survival of three out of five animals.

For the Marburg virus, the strategy was the same. The molecule of PMO AVI-6003, the most effective on mice and guinea pigs, has a survival rate of over 90%. The tests were subsequently conducted on macaques crabbers indicate that the treatment is 100% effective, as all 13 monkeys survived, the PMO was administered before or after the virus.

For Ebola, the figure is too low at 60% survival. However, the work presented in the journal Nature Medicine, are encouraging. Active even after infection, these treatments could not only help scientists potentially contaminated due to poor handling in the laboratory (an event which has happened in the past), but also fight against epidemics in Africa if it can be sufficiently earlier. Clinical trials should be done quickly because the molecules have already obtained the green light from the Food and Drug Administration (FDA)