PDCD1 and coinfection: An effector memory T cell-restricted upregulation of PD1 was also described for HCV/HIV-coinfection, where PD1 upregulation on CD8 T cells resulted in a diminished proliferation rate, reduced CD8 T cell degranulation measured by CD107a-expression and reduced interleukin-2 and interferon-y (INF-γ) levels (Saha et al., 2013).