Of note, antibodies targeting the group 1/class 4 epitope were found to be consistently effective at mediating infection of monocytes/macrophages, which may be partly explained by the necessity for at least two of the three RBD monomers in the trimer to be in the “up” position—the conformation required for engagement with cell surface receptors and subsequent proteasomal cleavage - in order for antibodies to bind to this region41,42,46,67,68. Here, CD177 is linked to infection.