U.S. health officials have asked three advanced biology laboratories to submit plans for producing the experimental Ebola drug ZMapp, which ran out after it was given to a handful of medical workers who contracted the disease in West Africa, government and lab officials said on Friday.

Under the "task order" issued on Thursday by the Biomedical Advanced Research and Development Authority (BARDA), a state-of-the-art manufacturing center in Texas will submit plans for manufacturing ZMapp, said Dr. Brett Giroir, chief executive officer of Texas A&M Health Science Center, which houses the lab. The lab works in conjunction with Britain's GlaxoSmithKline Plc.

One of three Centers for Innovation in Advanced Development and Manufacturing established by U.S. health officials in 2012 with $440 million in seed money, the Texas lab "is swiftly responding" to the request, Giroir said in a statement, and will submit detailed proposals for scaling up production of ZMapp.

ZMapp was given to American medical workers Dr. Kent Brantly and Nancy Writebol, who recovered after contracting Ebola in Liberia, and to at least one Spanish priest, who died. It has been held out as a promising therapy that could be made available during the worst Ebola outbreak on record, which has killed more than 4,500 people in West Africa.

Doctors treating Ebola patients say it is impossible to know whether ZMapp helped because it has not been studied in a rigorous clinical trial.

The U.S. government "is working with partners around the world as quickly as possible to advance the development of multiple vaccine and therapeutic candidates for clinical evaluation and future use in preventing or treating Ebola virus disease," BARDA Director Robin Robinson said in a statement.

The two other U.S. emergency drug manufacturing centers are a facility led by Emergent Biosolutions in Baltimore and a second in Holly Springs, North Carolina, led by Swiss drug company Novartis AG. Representatives of those two labs were not immediately available for comment.

Once proposals are submitted on Nov. 10, BARDA would then select one or more of the labs to start producing ZMapp, which is currently manufactured in tobacco plants by Kentucky Bioprocessing, a unit of Reynolds American Inc.

"We are prepared to take action immediately to ramp up production on this promising experimental drug for those in need of Ebola therapies," Giroir said.

Texas A&M's facility and the other two centers are required to develop the capacity to produce 50 million doses of pandemic influenza vaccine within four months and, more generally, to develop flexible manufacturing capabilities to allow them to produce countermeasures against chemical, biological, radiological, and nuclear threats.

San Diego-based Mapp Biopharmaceutical has said it ran out of its limited supply of ZMapp in August. Last week, the company said it was working with the government to increase production of the cocktail of three anti-Ebola antibodies, including by developing an alternative to production in tobacco plants. Mapp officials were not available for comment.

Texas has teamed up with Caliber Biotherapeutics of Bryan, Texas, on tobacco plant-based manufacturing.