Adenovirus E1B-55K regulates p53-dependent and -independent gene expression during infection

Human adenoviruses (HAdVs) are widespread pathogens with the capacity to manipulate host cellular pathways, including critical tumor suppressor networks. Among HAdV-encoded proteins, E1B-55K is a multifunctional viral oncoprotein that modulates both p53-dependent and -independent pathways during cell transformation. Here, we elucidate the dual role of E1B-55K in disrupting host defenses, focusing on its impact on p53 signaling and interferon-stimulated genes (ISGs) during infection. Using RNA-seq and follow-up wet lab experimental validation in A549 (p53 wildtype) and H1299 (p53-null) cells infected with wildtype HAdV-C5 or an E1B-55K-deficient mutant, we show that E1B-55K suppresses p53-mediated transcriptional responses, promoting cell survival and viral replication. Concurrently, E1B-55K modulates ISG expression, impairing the antiviral state in a p53-dependent manner. Our results reveal that E1B-55K leverages cellular context to optimize viral replication by targeting host tumor suppressor and innate immune pathways. This study uncovers a previously underappreciated aspect of E1B-55K function during infection, offering insights into its context-dependent repressive activity and solidifying its role as a multifunctional viral oncoprotein with broader implications for the HAdV replication cycle.