VIRUS, IN the immortal words of the British Nobel laureate Peter Medawar, is “a piece of bad news wrapped up in a protein.” Actually, a lot of viruses are not bad news at all, at least not to humans. Viruses are a little weird, not quite living but by no means dead. Outside living cells, they are just inert things. They don’t eat or breathe or do much of anything. They have no means of locomotion.
