DNA vaccines with a kick

Less is more. This is particularly true for DNA vaccines, where the aim is to deliver as small an amount of vector as possible to evoke a potent and protective immune response. Two recent reports demonstrate that DNA vaccine efficacy can be greatly enhanced using plasmids designed to launch self-replicating viral RNA expression vectors. Work published in the Journal of Virology by our group and results presented here by Berglund et al. demonstrate that significantly smaller doses of alphavirus-based plasmid DNA vectors are necessary to achieve protection in mice than conventional DNA vectors. These papers not only validate alphaviruses as a DNA vaccine approach, but also illustrate the broad utility of alphavirus vector technology developed over the past few years.