(A) PARP1 binds to KSHV terminal repeats (TR) and catalyzes the ADP-ribosylation of LANA, reducing KSHV replication in the latency. (B) PARP1 and Ste20-like human kinase homologous to kinases from chicken (hKFC) together bind to and ADP-ribosylate/phosphorylate KSHV RTA protein, which suppresses RTA-mediated KSHV lytic reactivation. (C) PARP1 binds to EBV BZLF1 promoter to prevent its transcription, thus inhibiting EBV lytic reactivation; the viral protein Zta is sufficient to prevent PARP1 binding to the BZLF1 promoter, driving robust BZLF1 expression and lytic reactivation. (D) HBV DNA promotes Ku70/80 and PARP1 to activate interferon regulatory factors (IRFs), which induces chemokine CCL3 and CCL5 levels. (E) ORF49 or PF-8 binds to PARP1, and prevents PARP1 from interacting with RTA, which reduces PARylated RTA and enhances virus replication. (F) Upon IAV infection or overexpression of IAV HA, PARP1 interacts with HA and translocates from the nucleus to cytoplasm, further down-regulating interferon receptor IFNAR through proteasomal degradation. Created with BioRender.com.