Structural basis for HCMV Pentamer recognition by antibodies and neuropilin 2

ABSTRACT Human cytomegalovirus (HCMV) encodes for multiple surface glycoproteins and glycoprotein complexes 1, 2 . One of these complexes, the HCMV Pentamer (gH, gL, UL128, UL130 and UL131), mediates tropism to both epithelial and endothelial cells by interacting with the cell surface receptor neuropilin 2 (NRP2) 3, 4 . Despite the critical nature of this interaction, the molecular determinants that govern NRP2 recognition remain unclear. Here we describe the cryo-EM structure of NRP2 bound to the HCMV Pentamer. The high-affinity interaction between these proteins is calcium-dependent and differs from the canonical C-terminal arginine (CendR) binding that NRP2 typically utilizes 5, 6 . The interaction is primarily mediated by NRP2 domains a2 and b2, which interact with UL128 and UL131. We also determine the structures of four human-derived neutralizing antibodies in complex with the HCMV Pentamer to define susceptible epitopes. The two most potent antibodies recognize a novel epitope yet do not compete with NRP2 binding. Collectively, these findings provide a structural basis for HCMV tropism and antibody-mediated neutralization, and serve as a guide for the development of HCMV treatments and vaccines.