MTOR and viral infectious disease: Even though rapamycin has been commonly used in organ transplantation to prevent graft rejection (Augustine et al., 2007), several studies have reported that mTOR inhibition by treatment with low and continuous doses of rapamycin during the immune challenge of CD8+ T cells could improve the function and memory formation following viral infections or tumor challenges (Araki et al., 2009; Rao et al., 2010; Li et al., 2011; Turner et al., 2011; Bassett et al., 2012; Mattson et al., 2014; Shrestha et al., 2014).