title: A potent neutralizing IgM mAb targeting the N218 epitope on E2 protein protects against Chikungunya virus pathogenesis.
abstract: Chikungunya virus (CHIKV) is a medically important human viral pathogen that causes Chikungunya fever accompanied with debilitating and persistent joint pain. Host-elicited or passively-transferred monoclonal antibodies (mAb) are essential mediators of CHIKV clearance. Therefore, this study aimed to generate and characterize a panel of mAbs for their neutralization efficacy against CHIKV infection in a cell-based and murine model. To evaluate their antigenicity and neutralization profile, indirect enzyme-linked immunosorbent assay (ELISA), an immunofluorescence assay (IFA) and a plaque reduction neutralization test were performed on mAbs of IgM isotype. CHIKV escape mutants against mAb 3E7b neutralization were generated, and reverse genetics techniques were then used to create an infectious CHIKV clone with a single mutation. 3E7b was also administered to neonate mice prior or after CHIKV infection. The survival rate, CHIKV burden in tissues and histopathology of the limb muscles were evaluated. Both IgM 3E7b and 8A2c bind strongly to native CHIKV surface and potently neutralize CHIKV replication. Further analyses of 3E7b binding and neutralization of CHIKV single-mutant clones revealed that N218 of CHIKV E2 protein is a potent neutralizing epitope. In a pre-binding neutralization assay, 3E7b blocks CHIKV attachment to permissive cells, possibly by binding to the surface-accessible E2-N218 residue. Prophylactic administration of 3E7b to neonate mice markedly reduced viremia and protected against CHIKV pathogenesis in various mice tissues. Given therapeutically at 4 h post-infection, 3E7b conferred 100% survival rate and similarly reduced CHIKV load in most mice tissues except the limb muscles. Collectively, these findings highlight the usefulness of 3E7b for future prophylactic or epitope-based vaccine design.
authors: a Laboratory of Molecular RNA Virology and Antiviral Strategies, Department of Microbiology; Yong Loo Lin School of Medicine, National University Health System, National University of Singapore ; Singapore.
authors: Shirley
authors: S
authors: Lam
authors: a Laboratory of Molecular RNA Virology and Antiviral Strategies, Department of Microbiology; Yong Loo Lin School of Medicine, National University Health System, National University of Singapore ; Singapore.
authors: Min
authors: M
authors: Nyo
authors: a Laboratory of Molecular RNA Virology and Antiviral Strategies, Department of Microbiology; Yong Loo Lin School of Medicine, National University Health System, National University of Singapore ; Singapore.
authors: Patchara
authors: P
authors: Phuektes
authors: b Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research) ; Singapore.
authors: Chow Wenn
authors: CW
authors: Yew
authors: b Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research) ; Singapore.|c Hepatitis Viruses and Newly Emerging Viruses; Department of Microbiology; Yong Loo Lin School of Medicine, National University Health System, National University of Singapore ; Singapore.
authors: Yee Joo
authors: YJ
authors: Tan
authors: a Laboratory of Molecular RNA Virology and Antiviral Strategies, Department of Microbiology; Yong Loo Lin School of Medicine, National University Health System, National University of Singapore ; Singapore.|b Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research) ; Singapore.
authors: Justin Jang Hann
authors: JJ
authors: Chu
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000737:chemistry / Q000276:immunology*; D057134:Antibodies, Neutralizing / Q000008:administration & dosage / Q000737:chemistry / Q000276:immunology*; D000914:Antibodies, Viral / Q000276:immunology; D000915:Antibody Affinity / Q000276:immunology; D000918:Antibody Specificity / Q000276:immunology; D065632:Chikungunya Fever / Q000276:immunology* / Q000517:prevention & control / Q000821:virology; D002646:Chikungunya virus / Q000187:drug effects / Q000276:immunology* / Q000502:physiology; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000737:chemistry / Q000276:immunology*; D005455:Fluorescent Antibody Technique; D054884:Host-Pathogen Interactions / Q000187:drug effects / Q000276:immunology; D006801:Humans; D007075:Immunoglobulin M / Q000008:administration & dosage / Q000737:chemistry / Q000276:immunology*; D053208:Kaplan-Meier Estimate; D008807:Mice, Inbred BALB C; D008958:Models, Molecular; D009500:Neutralization Tests; D011485:Protein Binding / Q000276:immunology; D017434:Protein Structure, Tertiary; D014759:Viral Envelope Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D000939:Epitopes; D007075:Immunoglobulin M; D014759:Viral Envelope Proteins
keywords: envelope 2 protein; epitope; monoclonal antibody; virus pathogenesis