During the deadliest Ebola outbreak ever in western Africa, two American missionaries received an experimental drug called ZMapp. An Ebola expert explains how ZMapp is derived and how it fights the deadly virus. (Gillian Brockell and Pamela Kirkland/The Washington Post)

The manufacturer of the experimental Ebola drug ZMapp said Friday that it is trying to squeeze more production out of the tobacco plants used to create the medication and develop other ways of making the drug in an effort to boost supply.

The 32,000-square-foot facility in Kentucky where the monoclonal antibodies are created in specially grown tobacco plants has put all other business on hold since August and is devoting its entire capacity to producing the Ebola medication, according to Mapp Biopharmaceutical.

With the federal government’s help, the tiny San Diego company also is seeking additional capacity at a similar facility affiliated with the Texas A&M Center for Innovation in Advanced Development and Manufacturing, one of three government-funded biodefense centers.

Over the longer term, Mapp is trying to figure out a way to use Chinese hamster ovary cells, a more traditional method of producing antibodies, that would allow greater production, according to a statement issued by the company. The Bill and Melinda Gates Foundation is helping with that effort.

But as the spread of the epidemic in West Africa continues to outrace conventional methods of control, Mapp did not reveal how much of the drug it will be able to produce or how quickly. The same questions remain for TKM-Ebola and brincidofovir, the other drugs that have been given to human Ebola victims so far. As a result, experts are unclear about when drug treatments will become an effective weapon against the virus, which has killed more than 3,800 people since March.

More than a dozen drugs are being studied for treating Ebola and other filoviruses.

Thomas Geisbert, a professor at the University of Texas Medical Branch at Galveston who has researched Ebola for decades, said that even if the drug manufacturers are able to scale up quickly, he sees no prospect that the medications will halt the epidemic in West Africa. Even the vaccines that are under development won’t be available until 2015, at the earliest.

“It’s not the cure-all,” he said. “A magic bullet to get ourselves out of this isn’t going to happen.”

Seven people have been treated with ZMapp, a cocktail of three monoclonal antibodies that has shown promise against the virus in macaques. The patients included physician Kent Brantly and missionary Nancy Writebol, Americans who were infected in Liberia this summer and recovered after treatment in the United States. It is impossible to determine from that small sample whether the medication is even partly responsible for their ability to defeat the Ebola virus.

Thomas Eric Duncan, a Liberian who succumbed to the virus Wednesday in Dallas, was not given ZMapp “because it was not available,” said Texas Health Presbyterian Hospital, where Duncan was treated. Supplies of ZMapp were exhausted by mid-August.

Duncan was given brincidofovir, an experimental antiviral drug made by Chimerix that has killed Ebola in test tubes. So was Ashoka Mukpo, a freelance journalist who was infected with Ebola in Liberia and is in a hospital in Nebraska.

And a handful of patients, including U.S. physician Rick Sacra, have been given TKM-Ebola, which is made by the Canadian drug company Tekmira.

The Food and Drug Administration granted the three drug manufacturers permission to use the unapproved medications on humans even though their safety and effectiveness against Ebola has not been proven. All three hope to make their drugs more widely available, but their small size prevents them from flipping a switch and dramatically ramping up production.

Ebola’s catastrophic effect on the body

“Outside the U.S., we are currently in discussions and assessing the best way to provide brincidofovir to have a positive impact on public health,” said Joseph Schepers, executive director of investor relations and corporate communications for Chimerix.

ZMapp is produced by Kentucky BioProcessing, which owns the 32,000-square-foot facility. Mapp is seeking additional capacity at Caliber Biotherapeutics, which has a similar facility affiliated with the Texas A&M center.

The U.S. government’s Biomedical Advanced Research and Development Authority is funding both Tekmira and Mapp, which has a $24.9 million, 18-month contract from the agency to help it develop ZMapp as a protection against bioterrorism attacks. Tekmira has a $140 million contract with the Defense Department that was signed in 2010. After the Sept. 11, 2001, attacks, the government poured hundreds of millions of dollars into the development of these and other drugs. But budget cuts and the emergence of other priorities did not leave enough funding for the expensive final stages of clinical trials and for mass production, Geisbert said.

And since all previous Ebola outbreaks were relatively small and contained, there was no market for the drugs. Large companies left the job to smaller ones, such as Mapp and Tekmira. Now the demand is huge, and the companies and the government are racing to respond.

“It takes time,” said Geisbert, who was involved in the early development of numerous drugs for the virus when he worked for the Defense Department and who has conducted animal trials for TKM-Ebola. “You end up with a situation where these companies weren’t set up to ramp up [production]. You don’t just go from that to making 10,000 doses overnight.”

He believes Tekmira and Mapp appear to have the most promising Ebola treatments in the pipeline.

“I’ve got shelves and shelves full of stuff that can inhibit the growth of the virus in cell cultures,” Geisbert said. “Of those, there’s probably a dozen or so that can protect mice or guinea pigs with Ebola. But there’s only two so far that can protect against Ebola in non-human primates, and they are ZMapp and TKM-Ebola.”

Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said in an interview that even if the international community accelerates its response, “it’s conceivable that we will not be able to control it if we don’t put enough resources in. We might need to rely on a safe, effective vaccine.”

Researchers at the National Institutes of Health began a trial involving 20 people in early September to determine the safety of an Ebola vaccine that was already in the development pipeline. The initial results should be available later this fall. Two other vaccine trials — one begun Thursday in Africa — also are underway.

Abby Phillip and Joel Achenbach contributed to this report.