The hepatitis D virus possesses the smallest known human genome—only about 1,680 nucleotides encoding essentially a single protein. Yet from this remarkably limited genetic information emerges a molecular system capable of regulating genome copying, altering its developmental state, exploiting dozens of cellular pathways, and assembling new virus particles with extraordinary precision. The sophistication of HDV does not arise because either its RNA or its protein is independe

The hepatitis D virus RNA genome is continuously moving and negotiating interactions with other molecules. It is constantly sampling its own possible shapes while simultaneously engaging in dialogue with proteins that would respond to each of these shapes. These RNA shapes also interact with ions, water, and the three-dimensional architecture of the cell. To understand hepatitis D virus RNA is to appreciate that a single circular molecule of 1,680 nucleotides can simultaneous