title: Diagnostic potential and antigenic properties of recombinant tick-borne encephalitis virus subviral particles expressed in mammalian cells from Semliki Forest virus replicons.
abstract: The precursor membrane envelope (prME) proteins of all three tick-borne encephalitis virus (TBEV) subtypes were produced based on expression from Semliki Forest virus (SFV) replicons transcribed from recombinant plasmids. Vero E6 cells transfected by these plasmids showed specific reactivities in immunofluorescence and immunoblot assays by monoclonal antibodies against European and Far-Eastern subtype strains of TBEV, indicating proper folding of the expressed glycoproteins. The prME glycoproteins were secreted into the cell culture supernatant, forming TBEV subviral particles of 20 to 30 nm in diameter. IgM μ-capture and IgG monoclonal antibody (MAb)-capture enzyme immunoassays (EIAs) were developed based on prME Karelia-94 (Siberian subtype) particles. Altogether, 140 human serum samples were tested using these assays, and the results were compared to those obtained with a commercial IgM EIA, an in-house μ-capture IgM assay based on baculovirus-expressed antigen, a commercial IgG EIA, and a hemagglutination inhibition test. Compared to reference enzyme-linked immunosorbent assays (ELISAs), the sensitivities of the generated μ-capture IgM SFV-prME and IgG MAb-capture SFV-prME EIAs were 97.4 to 100% and 98.7%, respectively, and the specificities of the two assays were 100%. IgM and IgG immunofluorescence assays (IFAs) were created based on Vero E6 cells transfected with the recombinant plasmid carrying the TBEV Karelia-94 prME glycoproteins. The IgM IFA was 100% concordant with the μ-capture IgM bac-prME ELISA. The IgG IFA sensitivity and specificity were 98.7% and 100%, respectively, compared to those of the commercial ELISA. In conclusion, the tests developed based on SFV replicon-driven expression of TBEV glycoproteins provide safe and robust alternatives for conducting TBEV serology.
authors.affiliation: Haartman Institute, Department of Virology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
authors.forename: Lev
authors.initials: L
authors.lastname: Levanov
authors.forename: Suvi
authors.initials: S
authors.lastname: Kuivanen
authors.forename: Andrey
authors.initials: A
authors.lastname: Matveev
authors.forename: Sathyamangalam
authors.initials: S
authors.lastname: Swaminathan
authors.forename: Anu
authors.initials: A
authors.lastname: Jääskeläinen-Hakala
authors.forename: Olli
authors.initials: O
authors.lastname: Vapalahti
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D018929:Cell Culture Techniques; D002522:Chlorocebus aethiops; D004669:Encephalitis Viruses, Tick-Borne / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005455:Fluorescent Antibody Technique / Q000379:methods; D005822:Genetic Vectors; D006801:Humans; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D012672:Semliki forest virus / Q000235:genetics; D012680:Sensitivity and Specificity; D014709:Vero Cells; D014759:Viral Envelope Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D014764:Viral Proteins / Q000235:genetics / Q000302:isolation & purification; D022701:Virosomes / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D011994:Recombinant Proteins; D014759:Viral Envelope Proteins; D014764:Viral Proteins; D022701:Virosomes