Companies say it is too soon to know how many patients can be treated from one plasma donation, but it is likely no more than a few, at best. Emergent is hoping to avoid potential delays in plasma collection by also producing hyperimmune globulins in horses vaccinated with whole or partial bits of SARS-CoV-2. SAB takes this concept a step further, fully relying on its herd of genetically engineered cattle in Sioux Falls, South Dakota, as the source of its experimental hyperimmune therapy for COVID-19, which it expects will be ready for clinical testing this summer.
Others hope to avoid any supply limitations from donors—whether human, equine, or bovine. David Johnson, CEO of GigaGen, calls the hyperimmune approach “old school.” Hyperimmune therapies are one kind of polyclonal antibody therapy, in which many different antibodies targeting a virus are produced by many different B cells. GigaGen specializes in polyclonal antibody therapies that can be manufactured at scale in bioreactors. The start-up will collect blood from about 50 to 100 people that have recovered from COVID-19, find B cells that make antibodies for SARS-CoV-2, and then copy the genes from those B cells into genetically modified cell lines that crank out these virus-targeting antibodies in bioreactors.
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