1. Institute of Virology, Helmut-Ruska-Haus, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
2. Institute of Biotechnology, Graiciuno 8, 02241 Vilnius, Lithuania
3. Biomedical Research and Study Centre, University of Latvia, Ratsupites Str. 1, 1067 Riga, Latvia
4. Robert-Koch-Institut, Nordufer 20, 13353 Berlin, Germany