" A virus makes copies of itself inside a cell until eventually the cell gets pigged with virus and pops, and the viruses spill out of the broken cell. Or viruses can bud through a cell wall, like drips coming out of a faucet—drip, drip, drip, drip, copy, copy, copy, copy—that’s the way the AIDS virus works. "

― Richard Preston , The Hot Zone: The Terrifying True Story of the Origins of the Ebola Virus