Provides optimal viral replication conditions by promoting host cell survival and avoiding the host inflammatory response linked to NF-kappa-B activation. Blocks RIPK1 ubiquitination, thereby preventing NF-kappa-B activation and virally induced inflammatory response. Prevents host necroptosis by targeting RIPK3 thereby preventing the formation of necroptotic RIPK1-RIPK3 complexes. Also inhibits ZBP1-induced necroptosis. Does not have ribonucleotide reductase activity. Betaherpesviruses probably use another strategy to expand the dNTP pool in a quiescent host cell. Self-assembles into homo-oligomeric amyloid fibrils. Interacts with host RIPK1 (via RIP homotypic interaction motif); this interaction inhibits RIPK1 ubiquitination thereby preventing effective activation of host NF-kappa-B. Interacts with host RIPK3 (via RIP homotypic interaction motif); this interaction disrupts RIPK3-RIPK1 interactions characteristic of TNF-alpha induced necroptosis, thereby suppressing this death pathway. Interacts (via RIP homotypic interaction motif) with host ZBP1 (via RIP homotypic interaction motif); this interaction inhibits recruitment of RIPK1 and RIPK3 to ZBP1 and prevents ZBP1-induced NF-kappa-B activation. Starts to be expressed at 12 h after infection and accumulates in the cytoplasm of the infected cells. The N-terminal region drives rapid self-assembly into homo-oligomeric amyloid fibrils and interacts with the RHIMs of host kinases RIPK1 and RIPK3, and ZBP1 to form heteromeric amyloid fibrils. Undergoes proteolytic cleavage, generating two peptides, a N-terminal and a 116 kDa. The N-terminal peptide retains RIPK1- and RIPK3-binding activity as well as cell death suppression activity. Belongs to the ribonucleoside diphosphate reductase large chain family. Lacks the conserved sequence Asn-x-Cys-x-Glu essential for ribonucleotide reductase activity.