Credit: Cell Press A research group from Osaka University led by Professor Hisashi Arase and consisting of researchers from the Research Institute for Microbial Diseases, the Institute for Protein Research, the Immunology Frontier Research Center, the Center for Infectious Diseases, and the Graduate School of Medicine has discovered for the first time that both neutralizing antibodies that protect against infection as well as infection-enhancing antibodies that increase infectivity are produced after infection with SARS-CoV-2 by analyzing antibodies derived from COVID-19 patients. Antibodies against the receptor binding site (RBD) of the SARS-CoV-2 spike protein play an important function as neutralizing antibodies that suppress SARS-CoV-2 infection by inhibiting its binding to the human receptor, ACE2. On the other hand, the function of antibodies against other sites of the spike protein was unknown.