Vaccinia virus Genome sequencing

We report on the rapid, positive selection of a novel vaccinia virus genomic duplication mutant in the presence of the assembly inhibitor rifampin (also known as rifampicin). Until now, all known rifampin-resistant vaccinia virus isolates contain missense mutations in the D13L gene, which encodes a capsid-like scaffold protein required for stabilizing membrane curvature during the early stage of virion assembly. Here we describe a second pathway to rifampin-resistance involving A17, a membrane protein that anchors D13 to the immature virion. After one round of selection, a rifampin-resistant virus that contained a genomic duplication in the A17L-A21L region was recovered. The mutant had both C-terminal truncated and full-length A17L open reading frames.