CD8A and viral infectious disease: Endosome localized TLR3 is specialized for sensing and binding viral double-strand RNA (dsRNA) (Alexopoulou et al., 2001; Mielcarska et al., 2020), which is crucial for cross-priming of CD8+ T cells against virus infection (Schulz et al., 2005; Davey et al., 2010); Endo-lysosomal localized TLR11 recognizes and binds to profilin protein produced by Toxoplasma gondii, which initiates IL-12 production and induces the immune response against the parasite invasion (Yarovinsky et al., 2005).