The poliovirus replication machinery can escape inhibition by an antiviral drug that targets a host cell protein.

Viral replication depends on specific interactions with host factors. For example, poliovirus RNA replication requires association with intracellular membranes. Brefeldin A (BFA), which induces a major rearrangement of the cellular secretory apparatus, is a potent inhibitor of poliovirus RNA replication. Most aspects governing the relationship between viral replication complex and the host membranes remain poorly defined. To explore these interactions, we used a genetic approach and isolated BFA-resistant poliovirus variants. Mutations within viral proteins 2C and 3A render poliovirus resistant to BFA. In the absence of BFA, viruses containing either or both of these mutations replicated similarly to wild type. In the presence of BFA, viruses carrying a single mutation in 2C or 3A exhibited an intermediate-growth phenotype, while the double mutant was fully resistant. The viral proteins 2C and 3A have critical roles in both RNA replication and vesicle formation. The identification of BFA resistant mutants may facilitate the identification of cellular membrane-associated proteins necessary for induction of vesicle formation and RNA replication. Importantly, our data underscore the dramatic plasticity of the host-virus interactions required for successful viral replication.