PCNA and infection: An enrichment test of Pfam domains revealed many domain categories involved in the viral replication and integration process [recombinases, integrases, proliferating cell nuclear antigen (PCNA)], viral gene regulation (transcription factors), or some transporters [e.g., aquaporins/Major Intrinsic Protein (MIP)], which are likely critical to taking control of the host during infection (Fig. 2D) (51–53).