6UOE

3-25 Fab germline-reversion variant bound to an HCMV gB-derived peptide

Summary for 6UOE

• Entry DOI: 10.2210/pdb6uoe/pdb
• Descriptor: 3-25 Fab heavy chain, 3-25 Fab light chain, Envelope glycoprotein B, ... (6 entities in total)
• Functional Keywords: fragment antigen-binding, viral peptide, hcmv gb, immune system-viral protein complex, immune system/viral protein
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 3
• Total formula weight: 49908.46

Authors

Wrapp, D.,McLellan, J.S. (deposition date: 2019-10-14, release date: 2020-07-29, Last modification date: 2024-10-30)

Primary citation

Ye, X.,Su, H.,Wrapp, D.,Freed, D.C.,Li, F.,Yuan, Z.,Tang, A.,Li, L.,Ku, Z.,Xiong, W.,Jaijyan, D.,Zhu, H.,Wang, D.,McLellan, J.S.,Zhang, N.,Fu, T.M.,An, Z.
Recognition of a highly conserved glycoprotein B epitope by a bivalent antibody neutralizing HCMV at a post-attachment step.
Plos Pathog., 16:e1008736-e1008736, 2020

PubMed Abstract: Human cytomegalovirus (HCMV) is one of the main causative agents of congenital viral infection in neonates. HCMV infection also causes serious morbidity and mortality among organ transplant patients. Glycoprotein B (gB) is a major target for HCMV neutralizing antibodies, yet the underlying neutralization mechanisms remain largely unknown. Here we report that 3-25, a gB-specific monoclonal antibody previously isolated from a healthy HCMV-positive donor, efficiently neutralized 14 HCMV strains in both ARPE-19 cells and MRC-5 cells. The core epitope of 3-25 was mapped to a highly conserved linear epitope on antigenic domain 2 (AD-2) of gB. A 1.8 Å crystal structure of 3-25 Fab in complex with the peptide epitope revealed the molecular determinants of 3-25 binding to gB at atomic resolution. Negative-staining electron microscopy (EM) 3D reconstruction of 3-25 Fab in complex with de-glycosylated postfusion gB showed that 3-25 Fab fully occupied the gB trimer at the N-terminus with flexible binding angles. Functionally, 3-25 efficiently inhibited HCMV infection at a post-attachment step by interfering with viral membrane fusion, and restricted post-infection viral spreading in ARPE-19 cells. Interestingly, bivalency was required for HCMV neutralization by AD-2 specific antibody 3-25 but not the AD-4 specific antibody LJP538. In contrast, bivalency was not required for HCMV binding by both antibodies. Taken together, our results reveal the structural basis of gB recognition by 3-25 and demonstrate that inhibition of viral membrane fusion and a requirement of bivalency may be common for gB AD-2 specific neutralizing antibody.

PubMed: 32745149
DOI: 10.1371/journal.ppat.1008736

Experimental method

X-RAY DIFFRACTION (1.8 Å)