More studies in rodents and NHP are needed in order to establish the treatment window for the Tc bovine-derived fully human IgG. In summary, this study provides a proof of concept demonstrating that filovirus GP vaccine can be used in a Tc bovine production system to produce a fully human polyclonal IgG product that offers post-exposure protection against filovirus infection. can elicit protective and potent neutralizing fully human IgG antibodies rapidly and in commercially viable quantities. Ebolavirus (EBOV) belongs toEbolavirusgenus of the familyFiloviridaeand infects both humans and non-human primates (NHP) causing severe hemorrhagic fevers. Other symptoms of disease include sudden onset of fever, chills, headache, and anorexia followed by sore throat, vomiting, diarrhea, hemorrhaging, and the appearance of a petechial rash1,2,3. Filoviruses are categorized as Priority Class A pathogens by the Centers for Disease Control (CDC) and the National Institutes of Health (NIH); they present a clear biological KB-R7943 mesylate warfare threat with mortality approaching 6090% for certain viral subtypes4,5. The most recent outbreak of EBOV in Western Africa has clearly demonstrated that filoviruses pose a huge threat to public health worldwide. Presently, there are no licensed prophylactic Rabbit Polyclonal to MITF or therapeutic countermeasures for EBOV infections in humans. Effective countermeasures that can be rapidly produced in clinically relevant quantities, such as vaccines, antivirals and other prophylactic and therapeutic treatments, are top research priorities. In laboratory studies, treatment with multiple doses of KZ52, a human monoclonal antibody (Mab) derived from an EBOV survivor, prevented Ebola virus disease (EVD) in guinea pigs6; however, follow up studies in non-human primates (NHPs) failed to show measurable protection7. More recently, studies have demonstrated that purified macaque polyclonal IgG from convalescent monkey plasma, when given up to 48 hours post exposure, provides complete protection of NHP against filovirus challenge8. ZMapp (a cocktail of three humanized monoclonal antibodies produced in transgenic tobacco leaves) recently demonstrated a high level of protection in NHPs when given at 3 to 5 5 days after lethal challenge9,10,11. Convalescent plasma and ZMapp have been used in a small number of humans with EBOV infection, but logistical and production limitations have prevented widespread use12,13,14. Current immunoglobulin products, such as human intravenous immunoglobulin (IVIG), monoclonal antibodies, and animal-derived polyclonal antibodies (pAbs), have known limitations. For example, human pAb products require a large volume of plasma, KB-R7943 mesylate from many convalescent human donors with confirmed high titers, to make a KB-R7943 mesylate commercial product15,16. Although animal-derived pAbs could be an alternative, they typically have very high reactogenicity as animal-derived antibody products are foreign proteins in humans. This can cause a variety of adverse effects, such as severe allergic reactions (anaphylaxis)17,18. To avoid serious side effects, animal antibodies are usually processed into smaller F(ab) or F(ab)2fragments, but this often reduces their half-life and potency. Animal derived monoclonal antibodies can be humanized or chimerized to human Fc fragments to avoid side effects, however, they are directed against a single epitope and may be subject to rapid mutational escape. This has led to the development of oligoclonal cocktails, but similar to monoclonal products, there are difficulties developing and producing enough of the oligoclonal product in a timely manner to assist in an outbreak scenario. It is clear that an innovative and rapid approach, combining the good safety profile of human polyclonal antibody products with the high neutralizing antibody activity derived from hyperimmune animals, is needed. To address these limitations, SAB Biotherapeutics (SAB) has developed the Transchromosomic (Tc) bovine. The bovine immunoglobulin genes have been knocked out and a human artificial chromosome (HAC) containing the full germ line sequence of human immunoglobulin has been inserted, allowing the Tc bovines to produce fully human antibodies19,20,21,22. Like traditional animal systems used to produce polyclonal antibodies, Tc bovines can be hyperimmunized with vaccines containing strong adjuvants and/or immune stimulators, over an extensive period of time. The Tc bovine system was previously used to produce anti-hantavirus polyclonal human IgG with high neutralization titers. This product was protective in two animal models of lethal hantavirus disease23. The therapeutic efficacy of anti-hantavirus human polyclonal antibody clearly demonstrated the proof-of-concept that it is possible to produce a candidate KB-R7943 mesylate anti-viral biologic rapidly at high and scalable levels. In this study, two Tc bovines were hyperimmunized with a vaccine containing nanoparticles comprised of recombinant full length EBOV/Makona GP. Fully human pAbs against EBOV, with high titers in a GP-specific ELISA, were generated and purified. The pAbs were then evaluatedin vitrousing virus neutralization assays andin vivousing a lethal mouse model challenged with maEBOV. It was shown that intraperitoneal (i.p.) administration of the purified fully human.