Ebola matrix protein. Molecular model of the Ebola virus matrix protein VP40 (green) bound to RNA (ribonucleic acid, red). This membrane-associated protein is thought to be necessary for the assembly and budding of viral particles. This molecule is made from eight subunits and forms a pore-like structure. Ebola causes a severe, and often fatal disease in humans and nonhuman primates (monkeys, gorillas and chimpanzees).