THE GOOD VIRUS

An enthusiastic account of organisms that silently rule the Earth.

Viruses are “smaller than the wavelength of light,” and they replicate by invading a cell, multiplying, and then leaving, often killing the cell. A minuscule fraction cause human disease—polio, measles, flu, Covid-19, some cancers—but most are benign and often an essential part of life. Human viruses receive plenty of attention, but science journalist Ireland hits pay dirt by focusing on those that attack bacteria. Called bacteriophages or “phages,” they often attack deadly human infections. In 1917, scientists discovered that certain liquids, filtered to remove bacteria, destroyed bacterial cultures. They theorized that the fluid contained viruses that were “too small to see with a light microscope.” Researchers took up the idea of using these liquids to treat human infections. “For a few decades in the early twentieth century,” writes the author, “the world went mad for phages, and phage therapy was everywhere.” But phages are tricky. Some are weakly infectious; others are “hyper-specific, targeting only particular strains.” At the time, technology was primitive, and governments were lax about preclinical testing. By the 1930s, antibiotics appeared, miraculous drugs that made infections vanish. Sadly, by the 1990s, their vast overuse in medicine and agriculture was producing a deadly epidemic of increasingly resistant and even entirely impervious bacteria. Inevitably, this revived interest in phages. Both optimistic and realistic, Ireland writes that designing a phage for a specific bacterial strain is more complex than developing an antibiotic, and clinical trials have proven frustrating and expensive. He describes dramatic cures but no breakthroughs so far. At the halfway point of the book, the author rewinds the clock to the 1930s, describing genetic and DNA–related phage research that has led to numerous Nobel Prizes and an ongoing scientific revolution that has extended from the discovery of the double helix to genetic engineering, cloning, and insights into the nature of life itself.

A capably guided tour of a scientific wave of the future.