Structural basis for the inhibition of poxvirus assembly by the antibiotic rifampicin

Significance Most antibiotics do not interfere with viral infections. Rifampicin is a notable exception, as it inhibits several poxviruses, including the causative agent of smallpox. However, the inhibition of viral assembly is unrelated to the antibacterial activity of rifampicin against microbial RNA polymerases. Here, we reveal how the antibiotic prevents the recruitment of an essential scaffolding protein to nascent viral membranes. Based on these results, we provide a structural model of membrane assembly that is distinct from budding through cellular membranes and is most likely conserved in many large DNA viruses. Together, the mechanism of membrane assembly and structural models provide avenues to develop broad spectrum inhibitors against human and animal poxviruses.