title: Delineation of an epitope on domain I of Japanese encephalitis virus Envelope glycoprotein using monoclonal antibodies.
abstract: The Envelope glycoprotein (E-protein) of Japanese encephalitis virus (JEV) is the major structural component on the virion surface and is a primary target for the host immune system. Two monoclonal antibodies (MAbs) NHA-I (IgG2b) and NHA-II (IgM) against JEV (Indian strain 733913) were earlier developed in the authors' laboratory and found to be cross-reactive to nuclear histones. However, the epitope specificity of these MAbs has remained unknown. The present study was carried out to delineate the epitopes recognised by these MAbs on the E-protein of JEV strain 733913. The variable regions of the NHA-I and NHA-II were sequenced and the tertiary structures predicted. Molecular docking of the MAbs with the structural model of the JEV E-protein demonstrated that NHA-I binds to a predicted antigenic determinant (residue position 18-33) in domain-I. To understand the epitope specificity and check for possible cross-reactivity of these MAbs, comparative analysis of interactions with the known crystallographic structure of the West Nile virus (WNV) E-protein was also carried out. The studies predicted a differential binding of NHA-I but not of NHA-II between JEV and WNV. Mutagenesis studies could help analyse the specificity of NHA-I. The NHA-II appears to be cross-reactive as it docked in the groove region between domains I and III of both the JEV and WNV E-proteins. In laboratory assays, namely, ELISA and immunofluorescence assay both the MAbs reacted equally with JEV while the NHA-I did not show any reactivity with WNV. In silico results were thus validated by laboratory experiments. The present study would help in better understanding of virus-host interactions at the molecular level, and also be useful for the future design of vaccines as well as peptide based diagnostics.
authors.affiliation: Japanese Encephalitis Group, National Institute of Virology, Sus Road Campus, 130/1, Pashan, Pune 411021, India.
authors.forename: Roopesh Singh
authors.initials: RS
authors.lastname: Gangwar
authors.forename: Pratip
authors.initials: P
authors.lastname: Shil
authors.forename: Sarah S
authors.initials: SS
authors.lastname: Cherian
authors.forename: Milind M
authors.initials: MM
authors.lastname: Gore
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000302:isolation & purification; D000914:Antibodies, Viral / Q000276:immunology / Q000302:isolation & purification; D004664:Encephalitis Virus, Japanese / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D018604:Epitope Mapping; D000939:Epitopes / Q000276:immunology*; D007135:Immunoglobulin Variable Region / Q000737:chemistry / Q000235:genetics; D008562:Membrane Glycoproteins / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D017422:Sequence Analysis, DNA; D014759:Viral Envelope Proteins / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D000939:Epitopes; D007135:Immunoglobulin Variable Region; D008562:Membrane Glycoproteins; D014759:Viral Envelope Proteins; C080628:glycoprotein E, Japanese encephalitis virus