zmapp zmapp zmapp is an experimental biopharmaceutical drug comprising three chimeric monoclonal antibodies under development as a treatment for ebola virus disease. two of the three components were originally developed at the public health agency of canada's national microbiology laboratory (nml), and the third at the u.s. army medical research institute of infectious diseases; the cocktail was optimized by gary kobinger, a research scientist at the nml and underwent further development under license by mapp biopharmaceutical. zmapp was first used on humans during the western african ebola virus epidemic, having only been previously tested on animals and not yet subjected to a randomized controlled trial. the national institutes of health (nih) ran a clinical trial starting in january 2015 with subjects from sierra leone, guinea, and liberia aiming to enroll 200 people, but the epidemic waned and the trial closed early, leaving it too statistically underpowered to give a meaningful result about whether zmapp worked. schematic representation of how monoclonal antibodies are generally made from hybridomas. to make zmapp, the genes encoding for the antibodies were extracted from the hybridomas, genetically engineered to replace mouse components with human components, and transfected into tobacco plants. in 2016, a clinical study comparing zmapp to the current standard of care for ebola was inconclusive. chemistry the drug is composed of three monoclonal antibodies (mabs), initially harvested from mice exposed to ebola virus proteins, that have been chimerized with human constant regions. the components are chimeric monoclonal antibody c13c6 from a previously existing antibody cocktail called "mb-003" and two chimeric mabs from a different antibody cocktail called zmab, c2g4, and c4g7. zmapp is manufactured in the tobacco plant nicotiana benthamiana in the bioproduction process known as "pharming" by kentucky bioprocessing, a subsidiary of reynolds american. mechanism of action like intravenous immunoglobulin therapy, zmapp contains a mixture of neutralizing antibodies that confer passive immunity to an individual, enhancing the normal immune response, and is designed to be administered after exposure to the ebola virus. such antibodies have been used in the treatment and prevention of various infectious diseases and are intended to attack the virus by interfering with its surface and neutralizing it to prevent further damage.the nicotiana benthamiana tobacco plant history two of the drug's three components were originally developed at the public health agency of canada's national microbiology laboratory (nml), and a third at the u.s. army medical research institute of infectious diseases; the cocktail was optimized by gary kobinger, then branch chief of the nml, and is undergoing further development by leaf biopharmaceutical (leafbio, inc.), a san diego-based arm of mapp biopharmaceutical. leafbio created zmapp in collaboration with its parent and defyrus inc., each of which had licensed its own cocktail of antibodies, called mb-003 and zmab. mb-003 mb-003 is a cocktail of three humanized or human–mouse chimeric mabs: c13c6, h13f6, and c6d8. a study published in september 2012 found that rhesus macaques infected with ebola virus (ebov) survived when receiving mb-003 (mixture of 3 chimeric monoclonal antibodies) one hour after infection. when treated 24 or 48 hours after infection, four of six animals survived and had little to no viremia and few, if any, clinical symptoms. mb-003 was created by scientists at the u.s. army medical research institute of infectious diseases, gene olinger, and jamie pettitt in collaboration with mapp biopharmaceutical with years of funding from us government agencies including the national institute of allergy and infectious disease, biomedical advanced research and development authority, and the defense threat reduction agency. zmab zmab is a mixture of three mouse mabs: m1h3, m2g4, and m4g7. a study published in november 2013 found that ebov-infected macaque monkeys survived after being given a therapy with a combination of three ebov surface glycoprotein (ebov-gp)-specific monoclonal antibodies (zmab) within 24 hours of infection. the authors concluded that post-exposure treatment resulted in a robust immune response, with good protection for up to 10 weeks and some protection at 13 weeks. zmab was created by the nml and licensed to defyrus, a toronto-based biodefense company, with further funding by the public health agency of canada. zmapp a 2014 paper described how mapp and its collaborators, including investigators at public health agency of canada, kentucky bioprocessing, and the national institute of allergy and infectious diseases, first chimerized the three antibodies comprising zmab, then tested combinations of mb-003 and the chimeric zmab antibodies in guinea pigs and then primates to determine the best combination, which turned out to be c13c6 from mb-003 and two chimeric mabs from zmab, c2g4 and c4g7. this is zmapp. in an experiment also published in the 2014 paper, 21 rhesus macaque primates were infected with the kikwit congolese variant of ebov. three primates in the control arm were given a non-functional antibody, and the 18 in the treatment arm were divided into three groups of six. all primates in the treatment arm received three doses of zmapp, spaced 3 days apart. the first treatment group received its first dose on 3rd day after being infected; the second group on the 4th day after being infected, and the third group, on the 5th day after being infected. all three primates in the control group died; all 18 primates in the treatment arm survived. mapp then went on to show that zmapp inhibits replication of a guinean strain of ebov in cell cultures. mapp remains involved in the production of the drug through its contracts with kentucky bioprocessing, a subsidiary of reynolds american. to produce the drug, genes coding for the chimeric mabs were inserted into viral vectors, and tobacco plants are infected with the viral vector encoding for the antibodies, using agrobacterium cultures. subsequently, antibodies are extracted and purified from the plants. once the genes encoding the chimeric mabs are in hand, the entire tobacco production cycle is believed to take a few months. the development of these production methods was funded by the u.s. defense advanced research projects agency as part of its bio-defense efforts following the 9/11 terrorist attacks. use during the 2014–16 ebola outbreak in west africa