CD8A and viral infectious disease: They also produce type I interferon (IFN) in response to viral infections, activate CD8+ T cells, and cross-present cell-associated viral and tumor antigens to CD8+ T cells (Asano et al., 2011, Backer et al., 2010, Bernhard et al., 2015, Honke et al., 2012, Junt et al., 2007).