Anti-SARS-CoV-2 antibodies in a nasal spray efficiently block viral transmission between ferrets.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to spread in the population. We recently reported the production of bovine colostrum-derived antibodies that can neutralize the virus. These have been formulated into a nasal spray. The immunoglobulin preparation is capable of blocking interaction of the trimeric spike protein (Tri S) of SARS-CoV-2 with the cellular receptor angiotensin-converting enzyme 2 (ACE2), entry of a pseudovirus carrying the Tri S into ACE2 over-expressing human embryonic kidney (HEK) cells, and entry of the virus into live Vero E6 cells. Using an ELISA assay, we demonstrate here that this holds true for different SARS-CoV-2 variants of concern. Using the ferret transmission model, we show that the nasal spray formulation of anti-SARS-CoV-2 immunoglobulins efficiently blocks transmission of SARS-CoV-2 from infected to uninfected ferrets. The results indicate that the use of the nasal spray in humans can add an effective additional layer of protection against the virus, and might be applicable for other viruses of the upper respiratory tract.