Researchers Discover First Human Antibodies That Work Against All Ebolaviruses
- Category: Antibodies
- Published on Friday, 19 May 2017 09:20
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BRONX, NY, USA I May 18, 2017 I After analyzing the blood of a survivor of the 2013-16 Ebola outbreak, a team of scientists from academia, industry and the government has discovered the first natural human antibodies that can neutralize and protect animals against all three major disease-causing ebolaviruses. The findings, published online today in the journal Cell, could lead to the first broadly effective ebolavirus therapies and vaccines.
Ebolaviruses infections are usually severe and often fatal. There are no vaccines or treatments approved by the U.S. Food and Drug Administration for these viruses. Some two dozen ebolavirus outbreaks have occurred since 1976, when the first outbreak was documented in villages along the Ebola River in the Democratic Republic of Congo (formerly Zaire). The largest outbreak in history—the 2013-16 Western African epidemic—caused more than 11,000 deaths and infected more than 29,000 people.
Challenges in Targeting Ebolaviruses
Monoclonal antibodies, which bind to and neutralize specific pathogens and toxins, have emerged as one of the most promising treatments for Ebola patients. A critical problem, however, is that most antibody therapies target just one specific ebolavirus. For example, the most advanced therapy—ZMappTM, a cocktail of three monoclonal antibodies—is specific for Ebola virus (formerly known as "Ebola Zaire"), but doesn't work against two related ebolaviruses (Sudan virus and Bundibugyo virus) that have also caused major outbreaks.
"Since it's impossible to predict which of these agents will cause the next epidemic, it would be ideal to develop a single therapy that could treat or prevent infection caused by any known ebolavirus," says study co-leader Zachary A. Bornholdt, Ph.D., director of antibody discovery at Mapp Biopharmaceutical, Inc. "Our discovery and characterization of broadly neutralizing human antibodies is an important step toward that goal," adds study co-leader, Kartik Chandran, Ph.D., professor of microbiology & immunology at Albert Einstein College of Medicine.
The study was also co-led by John M. Dye, Ph.D., chief of viral immunology at the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID).
Antibodies with Broad Powers
In earlier research, Dr. Bornholdt and Laura M. Walker, Ph.D., a senior scientist at Adimab, LLC, isolated 349 distinct monoclonal antibodies from a survivor of the 2013-16 Ebola epidemic. In the current study, the multi-institutional research team found that two of those 349 antibodies, known as ADI-15878 and ADI-15742, potently neutralized infection by all five known ebolaviruses in tissue culture. Both antibodies were also able to protect animals (mice and ferrets) that had been exposed to a lethal dose of the three major agents: Ebola virus, Bundibugyo virus and Sudan virus.
Follow-up studies showed that the two antibodies isolated from the Ebola patient work by interfering with a critical step in the process by which ebolaviruses infect cells and then multiply inside them. The two antibodies encounter the virus while it's still in the bloodstream, and bind to glycoproteins (proteins to which carbohydrate chains are attached) that project from its surface. The virus, with its hitchhiking antibodies still bound to it, then attaches to a cell and enters the lysosome— a membrane-bound structure within the cell that is filled with enzymes for digesting foreign and cellular components. The virus must then fuse with the lysosome membrane to escape into the host cell's cytoplasm, where it can multiply. However, the antibodies prevent the virus from breaking out of its lysosomal "prison," thus stopping infection in its tracks.
Advancing Vaccine and Therapeutic Development
"Knowing precisely where the antibodies attach to the glycoprotein molecules and when and how they act to neutralize ebolaviruses, we can begin to craft broadly effective immunotherapies," says Dr. Dye. "That knowledge has already allowed us to create a cocktail of monoclonal antibodies that we are testing in larger animal models for possible use in treating infected patients," adds Dr. Bornholdt.
Dr. Chandran explains more about the findings in this video at http://www.einstein.yu.edu/gadgets/video/dcpa/?video=kartik-chandran-ebola
The researchers also pinpointed the human genes that are the likely source of the immune cells that produce the two antibodies. These and other findings could help speed the development of vaccines to prevent ebolavirus infection. "We'd like to synthesize vaccine immunogens [proteins that trigger antibody production] that can elicit the same types of broadly protective antibodies in people," says Dr. Chandran.
The study is titled "Antibodies from a human survivor define sites of vulnerability for broad protection against ebolaviruses." Other Einstein researchers include co-first author Anna Z. Wec, M.S., Elisabeth K. Nyakatura, Ph.D., Jens Maximilian Fels, Rohit K. Jangra, Ph.D., M.V.Sc., B.V.Sc. & A.H., and Jonathan R. Lai, Ph.D. Additional contributors are co-first author Andrew S. Herbert, Ph.D., Rebekah M. James, and Russell R. Bakken, of USAMRIID, Fort Detrick, MD; Shihua He, Ph.D., Marc-Antoine de La Vega, Wenjun Zhu, Ph.D., and Xiangguo Qiu, M.D., of National Microbiology Laboratory, Public Health Agency of Canada and University of Manitoba, Manitoba, Canada; Charles D. Murin, Ph.D., Hannah L. Turner, and Andrew B. Ward, Ph.D. of The Scripps Research Institute, La Jolla, CA; Eileen Goodwin of Adimab, LLC, Lebanon, NH; and Dafna M. Abelson and Larry Zeitlin, Ph.D. of Mapp Biopharmaceutical Inc., San Diego, CA.
The study was funded by grants from the National Institutes of Health (U19 AI109762), JSTO- Defense Threat Reduction Agency (CB4088 and HDTRA1-13-C-0018), and the Public Health Agency of Canada.
The authors declare no financial conflicts of interest.
About Albert Einstein College of Medicine
Albert Einstein College of Medicine is one of the nation's premier centers for research, medical education and clinical investigation. During the 2016-2017 academic year, Einstein is home to 717 M.D. students, 166 Ph.D. students, 103 students in the combined M.D./Ph.D. program, and 278 postdoctoral research fellows. The College of Medicine has more than 1,900 full-time faculty members located on the main campus and at its clinical affiliates. In 2016, Einstein received more than $160 million in awards from the National Institutes of Health (NIH). This includes the funding of major research centers at Einstein in aging, intellectual development disorders, diabetes, cancer, clinical and translational research, liver disease, and AIDS. Other areas where the College of Medicine is concentrating its efforts include developmental brain research, neuroscience, cardiac disease, and initiatives to reduce and eliminate ethnic and racial health disparities. Its partnership with Montefiore, the University Hospital and academic medical center for Einstein, advances clinical and translational research to accelerate the pace at which new discoveries become the treatments and therapies that benefit patients. Einstein runs one of the largest residency and fellowship training programs in the medical and dental professions in the United States through Montefiore and an affiliation network involving hospitals and medical centers in the Bronx, Brooklyn and on Long Island. For more information, please visit www.einstein.yu.edu, read our blog, follow us on Twitter, like us on Facebook and view us on YouTube.
About Mapp Biopharmaceutical
Mapp Biopharmaceutical develops monoclonal antibody products for the prevention and treatment of infectious diseases, focusing on unmet needs in global health and biodefense. The company has advanced two anti-viral antibody-based therapeutics into clinical trials, including a Phase 2 trial of ZMappTM in patients with Ebola Virus Disease. For more information, visit www.mappbio.com
About U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID)
USAMRIID's mission is to provide leading edge medical capabilities to deter and defend against current and emerging biological threat agents. Research conducted at USAMRIID leads to medical solutions-vaccines, drugs, diagnostics, and information-that benefit both military personnel and civilians. The Institute plays a key role as the lead military medical research laboratory for the Defense Threat Reduction Agency's Joint Science and Technology Office for Chemical and Biological Defense. USAMRIID is a subordinate laboratory of the U.S. Army Medical Research and Materiel Command. For more information, visit www.usamriid.army.mil
SOURCE: Albert Einstein College of Medicine