Skip to main content
Tufts Public Health

What Are Viruses and How Do They Work?

“A virus is just a piece of information,” said John Coffin. Here, an image of an isolate from the first U.S. case of COVID-19. The spherical viral particles, colorized blue, contain cross-section through the viral genome, seen as black dots. Photo: CDC
Friday, April 3, 2020

The novel coronavirus behind the COVID-19 pandemic is causing tremendous damage, killing tens of thousands of people, and upending economies as nations struggle to contain its spread. But on its own, like other viruses, it is inert, not even alive. Viruses gain their power by worming their way into living cells, quickly hijacking the cells’ machinery, then reproducing like mad. Soon they are spilling out into other cells, infecting them, too—and sometimes spreading across the world.

Viruses are potent because “they evolve quickly, they are unaffected by antibiotics, they can be elusive, they can be versatile, they can inflict extremely high rates of fatality, and they are fiendishly simple, at least relative to other living or quasi-living creatures,” the noted science writer David Quammen says in his 2012 book Spillover: Animal Infections and the Next Human Pandemic.

But what exactly are viruses? John Coffin, a virology researcher at the Tufts School of Medicine, says that at root a virus is simply “a piece of information.” Viruses are tiny—visible only with an electron microscope—and many contain as few as two to ten genes, compared to the 20,000 genes in each cell of a person.

A virus’ “business is to make more of itself—that’s its only job,” Coffin says. “Causing disease along the way may or may not be good for it.”

To understand more about viruses, Tufts Now spoke with Coffin, who is the American Cancer Society Professor of Molecular Biology and Microbiology at Tufts. In his research, he focuses on viruses such as the human immunodeficiency virus (HIV), which has killed more than 32 million people worldwide since the early 1980s.

Read More