CD8A and viral infectious disease: Here, the novel contributions of IgAN scRNA-seq are summarized: (1) ScRNA-seq reveals the dynamic landscape of immune cells, including the activation of B cells (pathway enriched in viral infection) and Tfh cells, the active afferent and efferent signals of monocytes with (especially interferon induction gene), and the weakened cytotoxicity of CD8+ T cells (both in circulation and renal tissue) in IgAN patients.