CD226 and animal viral hepatitis: To assess the pattern of immune-modulatory receptor expression of virus-specific CD4+ T cells in viral hepatitis in more detail11,23–30, we analysed the co-inhibitory receptor TIGIT together with an array of different co-inhibitory molecules like PD-1, BTLA, Tim-3 as well as OX40 and CD226 (DNAM-1) on ex vivo bulk and MHC class II tetramer+ HCV-specific T cells24,31–40.