By specifically blocking neuropilin-1 with antibodies, the researchers were able to significantly reduce infection in laboratory cell cultures. “If you think of ACE2 as a door lock to enter the cell, then neuropilin-1 could be a factor that directs the virus to the door. ACE2 is expressed at very low levels in most cells. Thus, it is not easy for the virus to find doors to enter. Other factors such as neuropilin-1 might help the virus finding its door”, says Balistreri.
Since disorders in smelling are among the symptoms of COVID-19 and neuropilin-1 are known to be localized in the cell layer of the nasal cavity, the scientists examined tissue samples from deceased COVID-19 patients. “We wanted to find out whether cells equipped with neuropilin-1 are really infected by SARS-CoV-2, and found that this was the case, says Mika Simons, Professor of molecular neurobiology at the Technical University of Munich and co-leader of the study.