- Human trials for a new COVID-19 immunotherapy candidate (SAB-185) that is derived from genetically engineered cow plasma will begin in July 2020.
- The cows have been genetically engineered to produce human antibodies to fight off COVID-19.
- Plasma from the cows is expected to assist COVID-19 patients overcome the infection.
SAb Biotherapeutics (SAB), a biopharmaceutical company based in Sioux Falls, South Dakota has announced that human testing will begin on a new experimental therapy for people infected with COVID-19. In vitro data has demonstrated that its COVID-19 immunotherapy candidate derived from cattle, known as SAB-185, has highly potent neutralizing antibodies to the SARS-CoV-2 virus that is four times higher than the most potent human convalescent plasma serum (plasma from a recovering COVID-19 patient) sample.1
What is SAB-185 and How is It Made?
SAB-185 is an immunotherapy candidate for COVID-19 that was created based on the assumption that the antibodies generated after a a patient gets infected and recovers can assist other patients who get infected or be used as a prophylactic therapy to prevent future coronavirus infections.2 Instead of relying on human plasma donations from patients who have recovered from COVID-19, SAB-185 uses genetically engineered cattle to produce antibodies in large quantities.3
The process of developing SAB-185 involves injecting cattle with a COVID-19 vaccine every 28 days to trigger an immune response in order to produce antibodies that have the ability to fight against the SARS-CoV-2 virus.4
Dr. Eddie Sullivan, CEO and co-founder of SAb Biotherapeutics said, “The cows then produce a specifically targeted high-neutralizing antibody that can be used in patients.”5
SAb Biotherapeutics said that SAB-185 is developed from the original SARS-CoV-2 strain from Wuhan, China. However, laboratory success has been demonstrated against a mutated strain known as the Munich strain and company officials say that that SAB-185 has the potential to be useful when the virus mutates.6
Using Genetically Engineered Cattle to Produce COVID-19 Antibodies
In order for cattle to produce COVID-19 antibodies that may be useful in treating humans infected with COVID-19, SAb Biotherapeutics took skin cells from a cow, removed the genes that are responsible for creating cow antibodies and inserted an engineered artificial human chromosome that produces human antibodies instead.7 Thereafter, scientists put the DNA from those cells into a cow egg, created an embryo, and then implanted the embryo into a cow to start a pregnancy. Over the past two decades, Sab Biotherapeutics have produced hundreds of genetically identical cows that produce COVID-19 antibodies.8
Why are Cows the Animal of Choice?
According to SAb Biotherapeutics, cows are used to produce antibodies not just because they have more blood than smaller animals engineered to synthesize human versions of the proteins, but their blood can also contain twice as many antibodies per milliliter as human blood and that makes it an economically viable product.9 Dr. William Klimstra, immunologist at the University of Pittsburgh said, “Essentially, the cows are used as a giant bioreactor.”10
Researchers believe that cows can produce antibodies that mimic the manner in which the human body fights viruses.11 The journal Science Magazine stated:
Most companies trying to produce antibodies to combat COVID-19 have pinned their hopes on mass-producing identical copies of a single version, a so-called monoclonal antibody that homes in on and attaches tightly to a particular section of a virus. Instead of making just one antibody variety, the cows fashion polyclonal antibodies, a range of the molecules that recognize several parts of the virus.12
Some experts are skeptical about using cows to produce COVID-19 antibodies for use in humans. Dr. Manish Sagar, associate professor of medicine and microbiology at Boston University Medical Centers said that he will remain skeptical “until I see further proof that production of antibodies in cows is a lot more feasible and economically viable.”13
Currently, there are no antibody therapies generated in cows approved for use in the United States.14
Funding from the Department of Defense
SAb Biotherapeutics had already been working in partnership with the U.S. Department of Defense (DoD) to prepare its human polyclonal antibody platform for rapid responses to new infectious diseases when the COVID-19 pandemic was declared by the WHO and CDC in March 2020.15
The company was awarded expanded scope on their Rapid Response contract for their SAB-185 candidate to treat COVID-19 from the DoD Joint Program Executive Office for Chemical, Biological, Radiological, and Nuclear Defense (JPEO – CBRND) Joint Project Lead for Enabling Biotechnologies (JPL-EB). The funding of $9.4 million is supported by the Biomedical Advanced Research Development Authority (BARDA), part of the Assistant Secretary for Preparedness and Response (ASPR) at the U.S. Department of Health and Human Services.16
Dr. Eddie Sullivan, CEO of SAb Biotherapeutics said, “SAB has developed a unique system to naturally, rapidly, and consistently produce large amounts of targeted human antibodies without human donors, as we have done with MERS and Ebola.”17
Human trials for SAB-185 are expected to begin in July 2020. The company has not provided any more details on the sample size and duration of the trial.18
1 Press Release. SAB Biotherapeutics Confirms Neutralizing Antibodies to SARS-CoV-2 and Begins Clinical Manufacturing of Novel COVID-19 Therapeutic Candidate. Business Wire May 28, 2020.
2 Ellis J. Manufacturing under way in Sioux Falls for potential COVID-19 therapeutic. Sioux Falls Argus Leader May 29, 2020.
4 Genovese D. Cow plasma used for potential Covid-19 antibody treatment. Fox Business June 20, 2020.
6 See Footnote 2.
7 Cohen E. Human trials expected to start next month for Covid-19 treatment derived from cows’ blood. CNN June 16, 2020.
9 Leslie M. This cow’s antibodies could be the newest weapon against COVID-19. Science June 5, 2020.
15 Wong S. Behind SAB’s rapid response to COVID-19. BioCentury Apr. 24, 2020.
16 SAB Biotherapeutics Advances Therapeutic for COVID-19 in Partnership with Department of Defense and BARDA. MarketWatch Apr. 16, 2020.
18 Brown L. Human trials to start on coronavirus drug derived from cow blood. New York Post June 17, 2020.