Genetically modified cows are currently being used by an American biotech firm to produce human antibodies that subdue SARS-CoV-2, the pathogen causing Covid-19 – with plans to start clinical trials this summer.
SAB Biotherapeutics, a US firm based in Sioux Falls, South Dakota, genetically alters dairy cows so that certain immune cells carry the DNA that allows people to make antibodies.
That modification “enables the animals to manufacture large quantities of human antibodies against a pathogen protein injected into them”, the company claims.
Viral immunologist William Klimstra of the University of Pittsburgh, who has been analysing the bovine-made antibodies’ potency against SARS-CoV-2, said: “Essentially, the cows are used as a giant bioreactor.”
Eddie Sullivan, SAB Biotherapeutics’s president and CEO, said: “Cows make good antibody factories; and not just because they have more blood than smaller animals engineered to synthesise human versions of the proteins. Their blood can also contain twice as many antibodies per millilitre as human blood.”
In addition, the company says that the cows fashion “polyclonal antibodies”, a range of the molecules that recognise several parts of the virus.
“That’s the natural way that our bodies fight disease,” Sullivan claims. This diversity may make the cows’ proteins more powerful than monoclonal antibodies, he says, and they may remain effective even if a virus mutates.
In test tube studies, Klimstra and colleagues recently pitted the antibodies against so-called convalescent plasma from the blood of Covid-19 survivors.
Rich in polyclonal antibodies, the plasma is being tested in clinical trials as a treatment for the virus. The cow antibodies “were four times better than convalescent plasma at preventing the virus from entering cells”, the company announced last month.
The firm hopes to begin a clinical trial within the next couple of months, Sullivan says, and wants to test whether infusions of antibodies sifted from the cows’ blood prevent healthy people from getting infected by SARS-CoV-2 and prove beneficial for patients who are already sick.
