Select Quotes
Introduction
“A Contagious Living Fluid”
The cave has been effectively cut off from the biology of the outside world for millions of years. Yet Suttle’s trip was well worth the effort. After he prepared his samples of crystal water, he gazed at them under a microscope. He saw viruses—swarms of them. There are as many as 200 million viruses in every drop of water from the Cave of Crystals. – Page 12
Before Willner’s expedition, scientists had assumed the lungs of healthy people were sterile. Yet Willner discovered that, on average, people have 174 species of viruses in their lungs. Only 10 percent of the species Willner found bore any close kinship to any virus ever found before. The other 90 percent were as strange as anything lurking in the Cave of Crystals. – Page 13
So far, scientists have officially named a few thousand species of viruses, but the true total may, by some estimates, reach into the trillions. – Page 13
“The old distinction between death and life loses some of its validity,” – Page 18
Old Companions
The Uncommon Cold
Scientists have gathered a great deal of evidence that children who get sick with relatively harmless viruses and bacteria may be protected from immune disorders when they get older, such as allergies and Crohn’s disease. – Page 28
Looking Down From The Stars
There are over 130 subtypes of influenza circulating among human beings, and each flu season a few of them dominate the viral population. – Page 31
Starting in 2005, for example, a strain of bird flu called H5N1 began to sicken hundreds of people in Southeast Asia. While it was very dangerous to those who got infected, it never once managed to move from one person to another. – Page 33
Everywhere, In All Things
The Enemy Of Our Enemy
But they can only invade microbes that are not already carrying a temperate phage. Bordet’s experiment failed because his original stock of bacteria had a viral immunity. – Page 52
That pump just so happens to be the one that the bacteria use to push antibiotics out of their interior before they can cause any harm. Bacteria can evolve stronger resistance to antibiotics by making more of these pumps. Chan and his colleagues tested out their new phage in a dish of bacteria. If they exposed the bacteria to the phage, the microbes evolved fewer pumps to make it harder for the phage to infect them. But with fewer pumps, they became more vulnerable to antibiotics. Their study suggests that phages and antibiotics together could trap bacteria in an evolutionary conflict. – Page 55
The Infected Ocean
They came to agree there are somewhere in the neighborhood of 10,000,000,000,000,000,000,000,000,000,000 viruses in the ocean. It is hard to find a point of comparison to make sense of such a huge number. There are 100 billion times more viruses in the oceans than the grains of sand on all the world’s beaches. If you put the viruses of the oceans together on a scale, they would equal the weight of 75 million blue whales (there are less than 10,000 blue whales on the entire planet). And if you lined up all the viruses in the ocean end to end, they would stretch out 42 million light-years. – Page 59
The hosts of the ocean’s viruses have responded to this threat by evolving all manner of defenses. But the viruses have evolved ways to override them. Since each species follows an evolutionary escape route of its own, this race has helped produce a staggering diversity of marine viruses. – Page 61
Scientists have found that all living things have mosaics of genomes, with hundreds or thousands of genes imported by viruses. As far down as scientists can reach on the tree of life, viruses have been shuttling genes. – Page 63
Our Inner Parasites
these healthy chickens were not simply infected with avian leukosis virus in some of their cells; the genetic instructions for making the virus were implanted in all of their cells, and the birds passed those instructions down to their descendants. – Page 67
Each of us carries almost 100,000 fragments of endogenous retrovirus DNA in our genome, making up about 8 percent of our DNA. To put that figure in perspective, consider that the 20,000 protein-coding genes in the human genome make up only 1.2 percent of our DNA. – Page 70
The Viral Future
The Long Goodbye
After thousands of years of suffering and puzzling over smallpox, we have finally come to understand it and halt its relentless destruction. And yet, by understanding smallpox, we have ensured that it can never be utterly eradicated as a threat to humans. The knowledge we have gained about viruses has given smallpox its own kind of immortality. – Page 117
Epilogue
The Alien In The Water Cooler
All those nots added up to one great, devastating NOT. Viruses were not alive. – Page 124
The committee was drawing a stark line between viruses and the living world. But within a few years, the discovery of giant viruses blurred the line. – Page 125
It’s so much like a cell, in fact, that La Scola and his colleagues discovered in 2008 that it can be infected by a virus of its own. – Page 125
For virophages and cells, these studies suggest, the enemy of my enemy is my friend. Some host cells even permit virophages to use their own DNA to store their genes. The virophage genes only come to life when a giant virus infects their host. They assemble into new virophages to attack the invader. Another line blurred: is the virophage a virus of its own, or a weapon deployed by the host cell? – Page 126
Drawing dividing lines through nature can be scientifically useful, but when it comes to understanding life itself, those lines can end up being artificial barriers. Rather than trying to figure out how viruses are not like other living things, it may be more useful to think about how viruses and other organisms form a continuum. We humans are an inextricable blend of mammal and virus. – Page 126
Selected References
Virus: An illustrated guide to 101 incredible microbes. – Page 129