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VLP structure of Chikungunya virus complexed with C34 Fab, 2f block.
Structural highlights
FunctionA0A286S4J4_CHIKV Class II viral fusion protein. Fusion activity is inactive as long as E1 is bound to E2 in mature virion. After virus attachment to target cell and endocytosis, acidification of the endosome would induce dissociation of E1/E2 heterodimer and concomitant trimerization of the E1 subunits. This E1 trimer is fusion active, and promotes release of viral nucleocapsid in cytoplasm after endosome and viral membrane fusion. Efficient fusion requires the presence of cholesterol and sphingolipid in the target membrane. Fusion is optimal at levels of about 1 molecule of cholesterol per 2 molecules of phospholipids, and is specific for sterols containing a 3-beta-hydroxyl group.[ARBA:ARBA00055183] Constitutive membrane protein involved in virus glycoprotein processing, cell permeabilization, and the budding of viral particles. Disrupts the calcium homeostasis of the cell, probably at the endoplasmic reticulum level. This leads to cytoplasmic calcium elevation. Because of its lipophilic properties, the 6K protein is postulated to influence the selection of lipids that interact with the transmembrane domains of the glycoproteins, which, in turn, affects the deformability of the bilayer required for the extreme curvature that occurs as budding proceeds. Present in low amount in virions, about 3% compared to viral glycoproteins.[ARBA:ARBA00037269] Provides the signal sequence for the translocation of the precursor of protein E3/E2 to the host endoplasmic reticulum. Furin-cleaved E3 remains associated with spike glycoprotein E1 and mediates pH protection of the latter during the transport via the secretory pathway. After virion release from the host cell, the assembly protein E3 is gradually released in the extracellular space.[ARBA:ARBA00037518] Publication Abstract from PubMedChikungunya virus (CHIKV) is a mosquito-borne alphavirus that causes febrile illness and acute or chronic arthritis. Most therapeutics are still in the pre-clinical stage. In this study, we report the isolation of two neutralizing antibodies, C34 and C37, from a convalescent patient and investigate their mechanisms of action. Both C34 and C37 exhibit high neutralizing activities in vitro and demonstrate protective effects against CHIKV in a female mouse model. Our functional and structural studies reveal a mechanism that inhibits multiple stages of the virus infection cycle. Both antibodies bind with high affinity to an epitope spanning E2, E1, and the connecting beta-strands, facilitating intra- and inter-virion crosslinking. Cryo-EM structures additionally identify a minor patch located beneath the E3 binding site on E2, which is allosterically exposed upon E3 dissociation during virus maturation. Functional and structural data further suggest that binding to the CHIKV receptor, Mxra8, is obstructed due to a clash between the antibodies and the stalk region of Mxra8. Our results highlight the potential of antibody-based therapeutics against CHIKV and elucidate the mechanisms of monoclonal antibody protection. Neutralizing antibodies against Chikungunya virus and structural elucidation of their mechanism of action.,Han X, Ji C, Tian S, Wang F, Cao GP, Li D, Duan X, Tong Z, Qi J, Wang Q, Huang Q, Zhan BD, Gao GF, Yan J Nat Commun. 2025 Nov 3;16(1):9682. doi: 10.1038/s41467-025-64687-2. PMID:41184282[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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