The article discusses research being done on viral evolution. It references the study "Poxviruses deploy genomic accordions to adapt rapidly against host antiviral defences," by N. C. Elde and colleagues in the 2012 issue of the journal "Cell." It says that the study shows that Poxviridae, one of the members of double-stranded (ds) DNA viruses, has used a genomic accordion to gain an adaptive mutation.