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Cryo-EM structure of SARS-CoV-2 spike in complex with non-neutralizing NTD-directed CV3-13 Fab isolated from convalescent individual
Structural highlights
FunctionSPIKE_SARS2 attaches the virion to the cell membrane by interacting with host receptor, initiating the infection (By similarity). Binding to human ACE2 receptor and internalization of the virus into the endosomes of the host cell induces conformational changes in the Spike glycoprotein (PubMed:32142651, PubMed:32075877, PubMed:32155444). Uses also human TMPRSS2 for priming in human lung cells which is an essential step for viral entry (PubMed:32142651). Proteolysis by cathepsin CTSL may unmask the fusion peptide of S2 and activate membranes fusion within endosomes.[HAMAP-Rule:MF_04099][1] [2] [3] mediates fusion of the virion and cellular membranes by acting as a class I viral fusion protein. Under the current model, the protein has at least three conformational states: pre-fusion native state, pre-hairpin intermediate state, and post-fusion hairpin state. During viral and target cell membrane fusion, the coiled coil regions (heptad repeats) assume a trimer-of-hairpins structure, positioning the fusion peptide in close proximity to the C-terminal region of the ectodomain. The formation of this structure appears to drive apposition and subsequent fusion of viral and target cell membranes.[HAMAP-Rule:MF_04099] Acts as a viral fusion peptide which is unmasked following S2 cleavage occurring upon virus endocytosis.[HAMAP-Rule:MF_04099] Publication Abstract from PubMedEmerging evidence indicates that both neutralizing and Fc-mediated effector functions of antibodies contribute to protection against SARS-CoV-2. It is unclear whether Fc-effector functions alone can protect against SARS-CoV-2. Here, we isolated CV3-13, a non-neutralizing antibody, from a convalescent individual with potent Fc-mediated effector functions. The cryoelectron microscopy structure of CV3-13 in complex with the SARS-CoV-2 spike reveals that the antibody binds from a distinct angle of approach to an N-terminal domain (NTD) epitope that only partially overlaps with the NTD supersite recognized by neutralizing antibodies. CV3-13 does not alter the replication dynamics of SARS-CoV-2 in K18-hACE2 mice, but its Fc-enhanced version significantly delays virus spread, neuroinvasion, and death in prophylactic settings. Interestingly, the combination of Fc-enhanced non-neutralizing CV3-13 with Fc-compromised neutralizing CV3-25 completely protects mice from lethal SARS-CoV-2 infection. Altogether, our data demonstrate that efficient Fc-mediated effector functions can potently contribute to the in vivo efficacy of anti-SARS-CoV-2 antibodies. A Fc-enhanced NTD-binding non-neutralizing antibody delays virus spread and synergizes with a nAb to protect mice from lethal SARS-CoV-2 infection.,Beaudoin-Bussieres G, Chen Y, Ullah I, Prevost J, Tolbert WD, Symmes K, Ding S, Benlarbi M, Gong SY, Tauzin A, Gasser R, Chatterjee D, Vezina D, Goyette G, Richard J, Zhou F, Stamatatos L, McGuire AT, Charest H, Roger M, Pozharski E, Kumar P, Mothes W, Uchil PD, Pazgier M, Finzi A Cell Rep. 2022 Feb 15;38(7):110368. doi: 10.1016/j.celrep.2022.110368. Epub 2022 , Jan 25. PMID:35123652[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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