There is no approved vaccine or treatment for Ebola, the virus that has infected more than 13,000 people and killed nearly 5,000 in the West African countries of Guinea, Liberia, and Sierra Leone. The virus, which produces symptoms ranging from muscle pain to internal bleeding and organ failure, is very hard to detect until symptoms emerge between two to 21 days after a person contracts it. Only about half the people who contract the virus will survive. Vaccine research has been limited, but now companies, governments, and charities are fast-tracking drugs that could stop the worst Ebola outbreak in history.
Two U.S. aid workers who were infected while treating Ebola patients in Liberia recovered from the virus after taking the experimental drug ZMapp, although a Liberian doctor died after taking it. A Nature article published in August explained that the drug was successful at saving monkeys with Ebola, but the drug has not undergone trials of whether it is effective or even safe in humans. Therefore, the manufacturer Mapp Biopharmaceutical had only a limited supply of the drug that was exhausted in August. The therapy is based on three monoclonal antibodies—antibodies made to target specific proteins—that the company produced in tobacco plants. The pharmaceutical company Amgen says it has dedicated a staff of 12 to 14 people who will try to create antibodies for ZMapp via a different method using Chinese hamster ovary cells. The company says it will work on the project through the end of the year, but it is unclear when more of the antibody could be available for human trials.
Canada’s Tekmira Pharmaceuticals is making limited amounts of an Ebola drug. The U.S. Food and Drug Administration gave Tekmira permission to give this drug, known as TKM-Ebola, to a small number of people thought to have the virus. The drug is designed to specifically attack the Ebola variant involved in the West Africa outbreak using a method called RNA interference, or RNAi, which silences specific genes to shut down the production of proteins. A 2010 study published in the Lancet showed that the drug was successful at treating Ebola in primates, and Tekmira tested the safety of the drug in humans between January and May of this year. Although the FDA is allowing Tekmira to provide the drug to Ebola patients as an emergency measure, the regulator put the clinical trial on hold until the company provides more information about its research.
Other Experimental Drugs
Several drugs in development for other ailments could also be used to treat Ebola.
Fujifilm (the camera company also has a biotech arm) said in early October that a French nurse infected with Ebola was treated after taking its Avigan anti-flu drug along with other unapproved drugs. It plans to ramp up production of the drug for Ebola patients this fall.
The FDA is letting Chimerix begin testing whether a drug designed to fight other dangerous viruses can be used against Ebola.
BioCryst Pharmaceuticals received funding from the U.S. National Institute of Allergy and Infectious Diseases (NIAID) to test a compound called BCX4430 against Ebola. The drug inhibits the replication of Ebola’s genetic material and could be effective against other conditions, such as yellow fever. The company is beginning trials in primates.
The NIAID has started human trials to determine whether two different Ebola vaccine candidates are safe. One trial that began in September will test the immune response of 20 healthy adults after taking a vaccine being developed by GlaxoSmithKline. Researchers say it has shown good results in keeping primates safe from Ebola. The institute will publish initial data on safety and dosing of the vaccine by the end of the year and told the World Health Organization that it could start testing a vaccine on thousands of people to see how well it works as early as January. NIAID also started small-scale testing another vaccine called VSV-ZEBOV that was developed in Canada and is now licensed to NewLink Genetics. Neither vaccine can cause an Ebola infection in the trial subjects. The main goal of the trials is to determine the safety of the vaccines, and the participants will not be deliberately exposed to Ebola to see whether the vaccine works, according to the NIAID. But the agency will take blood samples of the subjects to see how their bodies respond to the vaccine regimen. More information on the GlaxoSmithKline vaccine can be found here, and details on the VSV-ZEBOV trial are available here.
Johnson & Johnson plans to produce more than a million doses of an Ebola vaccine next year and provide 250,000 doses for clinical trials by next May. The regimen combines a vaccine developed by Johnson & Johnson’s Janssen Pharmaceutical and a vaccine from Denmark’s Bavarian Nordic. In experiments at the National Institutes of Health, the vaccine combination completely shielded primates from a strain of Ebola similar to the one causing the West Africa outbreak, Johnson & Johnson says.
Drug companies say they have the resources to produce large quantities of Ebola vaccines relatively quickly. For instance, GlaxoSmithKline says it can start producing 230,000 doses per month by April. But the testing and approval of Ebola drugs likely will take longer than that. In the meantime, Sierra Leone’s government estimates that more than 20 people are dying of Ebola there every day, and the World Health Organization has estimated that new cases could rise to between 5,000 and 10,000 per week by December 1.
In the short term, improved diagnostic tests and hospital care for Ebola patients could have a bigger effect than new treatments or vaccines. Diagnosing the test today requires sending blood samples to labs. The results can be ready within hours, but the WHO says that health-care workers in areas of Liberia without these labs have had to wait as long as five days to receive a diagnosis. The U.S. Navy has helped set up mobile labs to cut down on this time frame, but health-care teams could greatly benefit from a rapid test that diagnoses Ebola within minutes. Corgenix Medical Corporation is working on such a test under a three-year, $2.9 million grant from the NIH. However, Corgenix’s chief executive has said that despite reports to the contrary, the test is not ready yet and is unlikely to be finalized in the near future.
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