Anti-HDV IgM as a marker of disease activity in hepatitis delta. por Anika Wranke, Benjamin Heidrich, Stefanie Ernst, Beatriz Calle Serrano, Florin Alexandru Caruntu, Manuela Gabriela Curescu, Kendal Yalcin, Selim Gürel, Stefan Zeuzem, Andreas Erhardt, Stefan Lüth, George V Papatheodoridis, Birgit Bremer, Judith Stift, Jan Grabowski, Janina Kirschner, Kerstin Port, Markus Cornberg, Christine S Falk, Hans-Peter Dienes, Svenja Hardtke, Michael P Manns, Cihan Yurdaydin, Heiner Wedemeyer, HIDIT-2 Study Group