This graphic shows structure of the Ebola virus, progressively stripping away the layers until all that is left is the RNA genome.

1. TOP GRAPHIC: VIRION, complete virus particle. Glycoprotein spikes (pink) project from the surface and allow the virus to attach to host cells.

2: VIRAL ENVELOPE: virus minus the glycoprotein spikes. The outer layer is the viral envelope, derived from the host cell. The envelope is shown in translucent green. It is a lipid bilayer.

3. MIDDLE GRAPHIC: MATRIX PROTEIN, shown in red. Matrix proteins protect the nucleocapsid. They interact with the nucleocapsid proteins and the overlying envelope.

4. NUCLEOCAPSID, pale purple. This is the helical core of the Ebola virus. It contains and protects the RNA genome.

5. BOTTOM GRAPHIC: GENOME, single stranded RNA molecule that contains the viral genes.