| Structural highlights
Function
[SPIKE_CVEMC] S1 attaches the virion to the cell membrane by interacting with host DPP4, initiating the infection.[1] S2 is a class I viral fusion protein. Under the current model, the protein has at least 3 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 plasma cell membranes (By similarity).
Publication Abstract from PubMed
Middle East Respiratory Syndrome coronavirus (MERS-CoV) causes a highly lethal pulmonary infection with approximately 35% mortality. The potential for a future pandemic originating from animal reservoirs or healthcare-associated events is a major public health concern. There are no vaccines or therapeutic agents currently available for MERS-CoV. Using a probe-based single B cell-cloning strategy, we have identified and characterized multiple neutralizing mAbs specifically binding to the receptor binding domain (RBD) or S1 (non-RBD) regions from a convalescent MERS-CoV-infected patient and from immunized rhesus macaques. RBD-specific mAbs tended to have greater neutralizing potency than non-RBD S1-specific mAbs. Six RBD-specific and five S1-specific mAbs could be sorted into four RBD and three non-RBD distinct binding patterns, based on competition assays, mapping neutralization escape variants, and structural analysis. We determined co-crystal structures for two mAbs targeting RBD from different angles and show they can only bind RBD in the "out" position. We then showed that selected RBD-specific, non-RBD S1, and S2-specific mAbs given prophylactically prevented MERS-CoV replication in lungs and protected mice from lethal challenge. Importantly, combining RBD- and non-RBD mAbs delayed the emergence of escape mutations in a cell-based virus-escape assay. These studies identify mAbs targeting different antigenic sites on S that will be useful for defining mechanisms of MERS-CoV neutralization, and for developing more effective interventions to prevent or treat MERS-CoV infections.IMPORTANCE: MERS-CoV causes a highly lethal respiratory infection for which no vaccines or antiviral therapeutic options are currently available. Based on continuing exposure from established reservoirs in dromedary camels and bats, transmission of MERS-CoV into humans and future outbreaks are expected. Using structurally-defined probes for the MERS-CoV Spike (S) glycoprotein, the target for neutralizing antibodies, single B cells were sorted from a convalescent human and immunized non-human primates (NHPs). mAbs produced from paired immunoglobulin gene sequences were mapped to multiple epitopes within and outside the receptor-binding domain (RBD) and protected against lethal MERS infection in a murine model following passive immunization. Importantly, combining mAbs targeting distinct epitopes prevented viral neutralization escape from RBD-directed mAbs. These data suggest that antibody responses to multiple domains on CoV Spike may improve immunity and will guide future vaccine and therapeutic development efforts.
Importance of neutralizing monoclonal antibodies targeting multiple antigenic sites on MERS-CoV Spike to avoid neutralization escape.,Wang L, Shi W, Chappell JD, Joyce MG, Zhang Y, Kanekiyo M, Becker MM, van Doremalen N, Fischer R, Wang N, Corbett KS, Choe M, Mason RD, Van Galen JG, Zhou T, Saunders KO, Tatti KM, Haynes LM, Kwong PD, Modjarrad K, Kong WP, McLellan JS, Denison MR, Munster VJ, Mascola JR, Graham BS J Virol. 2018 Mar 7. pii: JVI.02002-17. doi: 10.1128/JVI.02002-17. PMID:29514901[2]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Raj VS, Mou H, Smits SL, Dekkers DH, Muller MA, Dijkman R, Muth D, Demmers JA, Zaki A, Fouchier RA, Thiel V, Drosten C, Rottier PJ, Osterhaus AD, Bosch BJ, Haagmans BL. Dipeptidyl peptidase 4 is a functional receptor for the emerging human coronavirus-EMC. Nature. 2013 Mar 14;495(7440):251-4. doi: 10.1038/nature12005. PMID:23486063 doi:http://dx.doi.org/10.1038/nature12005
- ↑ Wang L, Shi W, Chappell JD, Joyce MG, Zhang Y, Kanekiyo M, Becker MM, van Doremalen N, Fischer R, Wang N, Corbett KS, Choe M, Mason RD, Van Galen JG, Zhou T, Saunders KO, Tatti KM, Haynes LM, Kwong PD, Modjarrad K, Kong WP, McLellan JS, Denison MR, Munster VJ, Mascola JR, Graham BS. Importance of neutralizing monoclonal antibodies targeting multiple antigenic sites on MERS-CoV Spike to avoid neutralization escape. J Virol. 2018 Mar 7. pii: JVI.02002-17. doi: 10.1128/JVI.02002-17. PMID:29514901 doi:http://dx.doi.org/10.1128/JVI.02002-17
|
