Spillover: Animal Infections and the Next Human Pandemic

by David Quammen

Virus particles are so tiny they can’t be seen, except by electron microscopy, which involves killing them, so their presence during isolation must be detected indirectly. You start with a small bit of tissue, a drop of blood, or some other sample from an infected victim. Your hope is that it contains the virus. You add that inoculum, like a dash of yeast, to a culture of living cells in a nutrient medium. Then you incubate, you wait, you watch. Often, nothing happens. If you’re lucky, something does. You know you’ve succeeded when the virus replicates abundantly and asserts itself sufficiently to cause visible damage to the cultured cells. Ideally it forms plaques, large holes in the culture, each hole representing a locus of virus-caused devastation. The process demands patience, experience, expensively exact bench tools, plus meticulous precautions against contamination (which can falsify results) or accidental release (which can infect you, endanger your co-workers, and maybe panic a town).