CD8+ T cell selection pressure is a major driving force for evolution of hepatitis C virus nonstructural proteins - Ruhl, M; Knuschke, T; Schewior, K; Wiese, M; Tenckhoff, H; Spengler, U; Nattermann, J; Hoffmann, D; Timm, J (Zeitschrift für Gastroenterologie, 2011)