To generate a hepatitis E virus (HEV) genotype 3 (HEV-3)-specific monoclonal antibody (mAb), the Escherichia coli-expressed carboxy-terminal part of its capsid protein was used to immunise BALB/c mice. The immunisation resulted in the induction of HEV-specific antibodies of high titre. The mAb G117-AA4 of IgG1 isotype was obtained showing a strong reactivity with the homologous E. coli, but also yeast-expressed capsid protein of HEV-3. The mAb strongly cross-reacted with ratHEV capsid protein derivatives produced in both expression systems and weaker with an E. coli-expressed batHEV capsid protein fragment. In addition, the mAb reacted with capsid protein derivatives of genotypes HEV-2 and HEV-4 and common vole hepatitis E virus (cvHEV), produced by the cell-free synthesis in Chinese hamster ovary (CHO) and Spodoptera frugiperda (Sf21) cell lysates. Western blot and line blot reactivity of the mAb with capsid protein derivatives of HEV-1 to HEV-4, cvHEV, ratHEV and batHEV suggested a linear epitope. Use of truncated derivatives of ratHEV capsid protein in ELISA, Western blot, and a Pepscan analysis allowed to map the epitope within a partially surface-exposed region with the amino acid sequence LYTSV. The mAb was also shown to bind to human patient-derived HEV-3 from infected cell culture and to hare HEV-3 and camel HEV-7 capsid proteins from transfected cells by immunofluorescence assay. The novel mAb may serve as a useful tool for further investigations on the pathogenesis of HEV infections and might be used for diagnostic purposes. KEY POINTS: • The antibody showed cross-reactivity with capsid proteins of different hepeviruses. • The linear epitope of the antibody was mapped in a partially surface-exposed region. • The antibody detected native HEV-3 antigen in infected mammalian cells.

Branch Bioanalytics and Bioprocesses 14476 Potsdam Germany

Faculty of Health Sciences Joint Faculty of the Brandenburg University of Technology Cottbus Senftenberg the Brandenburg Medical School Theodor Fontane and the University of Potsdam Potsdam Germany

German Federal Institute for Risk Assessment 10589 Berlin Germany

Hybrotec GmbH 14476 Potsdam Germany

Institute of Biotechnology Life Sciences Centre Vilnius University 02241 Vilnius Lithuania

Institute of Chemistry and Biochemistry Freie Universität Berlin 14195 Berlin Germany

Institute of Novel and Emerging Infectious Diseases Friedrich Loeffler Institut Federal Research Institute for Animal Health 17493 Greifswald Insel Riems Germany

Institute of Virology Charité Universitätsmedizin Berlin 10117 Berlin Germany

Micromun GmbH 17489 Greifswald Germany

Partner site Hamburg Lübeck Borstel Riems German Center for Infection Research 17493 Greifswald Insel Riems Germany

qpa bioanalytics GmbH 10585 Berlin Germany

RECETOX Faculty of Science Masaryk University 62500 Brno Czech Republic

Site Berlin German Center for Infection Research 10117 Berlin Germany

Surflay Nanotec 12489 Berlin Germany

UP Transfer GmbH an der Universität Potsdam 14469 Potsdam Germany

Zentrum für Pathobiochemie und Genetik Medizinische Universität Wien 1090 Wien Austria

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