(CNN) -- Two American missionary workers infected with the deadly Ebola virus were given an experimental drug that seems to have saved their lives.

Dr. Kent Brantly was given the medication, ZMapp, shortly after telling his doctors he thought he would die, according to a source familiar with his case. Within an hour, doctors say his symptoms -- labored breathing and a widespread rash -- dramatically improved. Nancy Writebol, another missionary working with Samaritan's Purse, received two doses of the medication and has also shown significant improvement, sources say.

As there is no proven treatment and no vaccine for Ebola, this experimental drug is raising lots of questions.

Who makes the drug?

 

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Why isn't there an Ebola vaccine?

 

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West African Ebola epidemic

The drug was developed by the biotech firm Mapp Biopharmaceutical Inc., which is based in San Diego. The company was founded in 2003 "to develop novel pharmaceuticals for the prevention and treatment of infectious diseases, focusing on unmet needs in global health and biodefense," according to its website.

Mapp Biopharmaceutical has been working with the National Institutes of Health and the Defense Threat Reduction Agency, an arm of the military responsible for weapons of mass destruction, to develop an Ebola treatment for several years.

Are there other experimental Ebola drugs out there?

Yes. In March, the NIH awarded a five-year $28 million grant to establish a collaboration between researchers from 15 institutions who were working to fight Ebola.

"A whole menu of antibodies have been identified as potentially therapeutic, and researchers are eager to figure out which combinations are most effective and why," a news release about the grant said.

Tekmira, a Vancouver-based company that has a $140 million contract with the U.S. Department of Defense to develop an Ebola drug, began Phase 1 trials with its drug in January. But the FDA recently halted the trial, asking for more information.

At least one potential Ebola vaccine has been tested in healthy human volunteers, according to Thomas Geisbert, a leading researcher at the University of Texas Medical Branch. And last week, the NIH announced a safety trial of another Ebola vaccine will start as early as September.

How does ZMapp work?

Antibodies are proteins used by the immune system to mark and destroy foreign, or harmful, cells. A monoclonal antibody is similar, except it's engineered in a lab so it will attach to specific parts of a dangerous cell, according to the Mayo Clinic, mimicking your immune system's natural response. Monoclonal antibodies are used to treat many different types of conditions.

This medicine is a three-mouse monoclonal antibody, meaning that mice were exposed to fragments of the Ebola virus and then the antibodies generated within the mice's blood were harvested to create the medicine.

Why did American missionary workers get the drug?

Many have asked why these two workers received the experimental drug when so many -- around 1,600 -- others in West Africa also have the virus.

Samaritan's Purse reached out to an NIH scientist who was on the ground in West Africa, according to the National Institute of Allergy and Infectious Diseases. "The scientist was able to informally answer some questions and referred them to appropriate company contacts to pursue their interest in obtaining experimental product," NIAID said.

The World Health Organization says it was not involved in the decision to treat Brantly and Writebol. Both patients had to give consent to receive the drug, knowing it had never been tested in humans before.

The process by which the medication was made available to the American patients may have fallen under the U.S. Food and Drug Administration's "compassionate use" regulation, which allows access to investigational drugs outside clinical trials.

Did doctors know it would work?

No. The drug had shown promise in primates, but even in those experiments, just eight monkeys received the treatment. In any case, the human immune system can react differently than primates', which is why drugs are required to undergo human clinical trials before being approved by government agencies for widespread use.

The two Americans' cases will be studied further to determine how the drug worked with their immune systems.

Will the drug be made available to other Ebola patients?

 

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It's unclear. Doctors "cannot start using untested drugs in the middle of an outbreak, for various reasons," World Health Organization spokesman Gregory Hartl said.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, says scientists have to be careful about assuming this drug will work in other patients as it appears to have worked in Brantly.

"Having worked with administering antibodies for people for a really long time, that would be distinctly unusual," he told CNN. "As we all know in medicine ... you have to withhold judgment."

Does the company have more vials of the drug?

The company has very few doses ready for patient use, Fauci told CNN. "Apparently the company is trying to scale up, (but) it's not easy to scale up to very large number of doses."

Who paid for the drug and how much did it cost?

We don't know. Samaritan's Purse covered the cost of Brantly and Writebol's evacuations but did not pay for the drug, according to a spokesman.

When a patient gets an experimental drug, the drug company can donate the product under compassionate use. Mapp Biopharmaceutical Inc. might have done that in this case.

Health insurance companies typically do not pick up the tab for treatments that have not been approved by the FDA. But they would usually cover the cost of any doctor fees associated with giving the drug and any costs associated with monitoring how the drug is working.

Would this drug stop the Ebola epidemic?

If it were widely available, it certainly couldn't hurt. An effective Ebola drug could help doctors treat the deadly virus, which is killing about 60% of the people infected in West Africa. But a vaccine would be a much more effective tool in stopping this, and future, epidemics.

Vaccines are given to healthy people to prevent them from ever becoming infected. One challenge with Ebola, experts say, is that companies don't believe they could make much money from developing a vaccine, so few companies show interest.

這個新的埃博拉病毒藥物問題
由雅克·威爾遜和丹尼爾Dellorto，美國有線電視新聞網
2014年8月4日 - 更新2233 GMT（0633 HKT）

資料來源：美國有線電視新聞網的AP
故事突出
埃博拉病毒藥物ZMapp是由總部設在聖地亞哥的一家公司開發的
其他公司也一直致力於開發治療埃博拉病毒
目前還不清楚該藥物是否會被給予其他的埃博拉患者
（CNN） -感染了致命的埃博拉病毒的兩名美國傳教士的工作人員分別給予實驗藥物，似乎保住了性命。
布蘭特利肯特博士給予藥物治療，ZMapp，告訴他的醫生，他以為他會死不久，據熟悉他的案件來源。不到一個小時，醫生說他的症狀 - 呼吸困難和廣泛的皮疹 - 顯著改善。南希Writebol，另一個傳教士與善普施的工作，接受兩個劑量的藥物，並也顯示顯著改善，消息人士說。
由於沒有有效的治療，也沒有疫苗埃博拉病毒，這種實驗性藥物是提高很多問題。
誰使DRU 克？
揭秘血可能救埃博拉患者 為什麼沒有一個埃博拉病毒的疫苗？ 埃博拉運輸隊說CNN報導 西部非洲的埃博拉疫情
該藥物是由生物技術公司開發的馬普生物製藥公司。，總部設在聖地亞哥。該公司成立於2003年“開發新的藥物，傳染病的預防和治療，專注於全球健康和生物防禦未被滿足的需求，” 根據其網站。
馬普生物製藥一直與衛生部和國家機構的國防威脅降低局，負責大規模殺傷性武器的軍人的手臂，開發一種埃博拉病毒的治療了好幾年。
還有沒有其他的實驗埃博拉藥了嗎？
是的。今年三月，美國國立衛生研究院獲得了為期五年的28000000美元撥款，以確定誰正在努力爭取埃博拉從15個機構的研究人員之間的合作。
“抗體的整個菜單已被確定為潛在的治療和研究人員都急於找出哪些組合是最有效的，以及為什麼，”關於授予一個新聞發布會上說。
Tekmira，溫哥華的公司，擁有1.4億美元合同與美國國防部部制定了埃博拉病毒的藥物，開始第1階段臨床試驗用藥物的一月。但是，FDA最近停止了試驗，要求獲得更多信息。
至少有一個潛在的埃博拉病毒疫苗在健康志願者進行了測試，按照托馬斯Geisbert，在德州大學醫療分部的主要研究員。上週，在美國國立衛生研究院公佈了安全性試驗的另一個埃博拉病毒的疫苗最快將在九月開始。
如何ZMAP p 的工作？
抗體是用免疫系統來標記和破壞外來或有害的細胞蛋白。單克隆抗體是相似的，除了它的設計在實驗室所以它會連接到一個危險的細胞的特定部分，根據梅奧診所，模仿你的免疫系統的自然反應。單克隆抗體可用於治療許多不同類型的條件。
該藥物是一種三小鼠單克隆抗體，這意味著只小鼠暴露於埃博拉病毒的片段，然後將小鼠的血液中所產生的抗體，收穫創建的藥。
美國傳教士工人為什麼拿到藥？
很多人問，為什麼這兩名工人接受實驗藥物有那麼多- 約1600 -人在西非也有病毒。
善普施伸出的美國國立衛生研究院的科學家是誰在西非的地面上，根據過敏和傳染病國家研究所。“這位科學家能非正式地回答一些問題，並轉介至合適的聯繫人，以追求自己獲得的實驗產品的興趣，”NIAID的說。
世界衛生組織說，它並沒有參與到布蘭特利治療和Writebol的決定。這兩名患者不得不同意接受該藥物，知道它從來沒有在人類身上測試過。
通過該藥物已提供給美國患者的過程中可能會根據美國食品和藥物管理局的“同情使用”的規定，允許進入臨床試驗外研藥物下降。
難道醫生知道它的工作？
第該藥曾在靈長類動物中顯露才華，但即使在這些實驗中，僅有8只猴子接受治療。在任何情況下，人的免疫系統可以有不同的反應比靈長類“，這就是為什麼藥物需要被批准的政府機構廣泛使用之前，進行人類臨床試驗。
這兩個美國人的情況下，將進一步研究，以確定藥物與他們的免疫系統是如何工作的。
請問DRU 克提供給其他埃博拉病毒的病人？
第二埃博拉患者航向美國 攝像頭可以幫助檢測埃博拉病毒？
目前還不清楚。醫生“無法啟動使用未經測試的藥物在爆發的中間，由於種種原因，”世界衛生組織發言人格雷戈里·哈特爾說。
安東尼·福奇博士，過敏和傳染病國家研究所所長說，科學家必須要小心，假設這種藥物將工作在其他病人，因為它似乎在布蘭特利工作。
“經過與管理抗體的人了很長一段時間的工作，這將是明顯的不尋常，”他告訴美國有線電視新聞網。“大家都知道，在醫學...你要隱瞞的判斷。”
公司是否有DRU更多的小瓶克？
公司擁有很少的劑量準備患者使用，福西告訴CNN。“顯然，該公司正試圖擴大規模，（但）它是不容易的擴展到非常多的劑量。”
誰支付的藥品，有多少做的餘弦噸？
我們不知道。善普施的覆蓋布蘭特利和Writebol的疏散成本，但沒有支付的藥品，根據發言人。
當病人得到一種實驗性藥物，製藥公司可以捐贈體恤下使用的產品。馬普生物製藥公司可能會做，在這種情況下。
健康保險公司通常不買單了，但沒有被FDA批准治療。但是，他們通常會支付與給予藥物相關的任何一個醫生的成本費，並與監控如何將藥物工作相關的任何費用。
將這種藥物阻止埃博拉疫情？
如果它被廣泛使用，它肯定不能傷害。一個有效的埃博拉病毒的藥物可以幫助醫生治療致命的病毒，這是造成約60％的感染者在西非的人。但是，疫苗將是一個更有效的工具在阻止這一點，未來的流行病。
疫苗是給健康人，以防止他們曾經受到感染。一個挑戰與埃博拉病毒，專家說，是企業不相信自己能夠賺到多少錢，從研製疫苗，所以很少有公司表現出興趣。