PARP9 and viral infectious disease: This condition showed that the SARS-CoV-2 Nsp3 protein is similar to PARP9 and can inhibit PARP9 through molecular mimicry, depleting M2 macrophages, and weakening interferon signaling, which then weakens the ability of the host to resist viral infection (Da Silva et al., 2020; Fehr et al., 2020).