A Planet of Viruses Paperback – April 30, 2012

This thin book consists of short chapters accompanied by stunning photos of viral individuals. You’ll find a lot of basic information here that often gets skipped in larger, more ponderous books on the subject.

You get a sense of the sheer ubiquity of viruses. They are even on a grain of sand. You’ll read how little we know about them, especially about the marine-dwelling viruses which generally seem to be unlike anything known on land. You’ll read about some of the reasons that human flu epidemics are so often associated with birds and pigs (avian flu, swine flu). There is some information here I hadn’t read before about the ways in which the HIV virus compromises the body’s system. There are suggestions about how and why viruses might be coming back as a means of treating bacterial diseases, now that so many of our antibiotics are failing to cure all the mutated varieties of bacterial infection we are facing.

There are other, incidental astonishing facts mentioned here that I found myself reading about for the first time. For example, on the very first page, Zimmer mentions the existence of “The Cave of Crystals” in Mexico’s Sierra de Naica range. This other-worldly cavern of immense, towering crystals is now largely unavailable for viewing. But as with the other subjects touched on in this book, Zimmer’s description will pique your interest and induce you to explore further.

I think this is an excellent book to introduce readers from ages 10 on up to the subject of viruses. The fascinating facts presented here might then help sustain their interest if they should choose to plunge into more academic studies of the subject.

In Mexico, just southeast of the city of Chihuahua is an amazing cave: the Cave of Crystals. Besides boulder sized crystals the cave has numerous pools of ancient water, isolated from the outside world for millions of years, the pools contain no fish or other life forms. Yet the water in these pools was found to harbor viruses, millions of viruses. That's how Carl Zimmer starts out his informative, well written, book A Planet of Viruses. Not so much a single narrative but a collection of essays on this unusual biological entity. Each essay starts out with false-color electron micrographs of different viruses. Delving into the "life" history of each specie, the author gives you a brief overview of how they develop, reproduce and, yes, evolve.
How many kinds of virus are there? The truth is, we don't know. There are new strains being discovered every day, most of which do not effect humans at all. But they are everywhere, in the air we breathe, in the water we drink, in our bodies and on our bodies. Some viruses are harmful, even lethal to the organism they use to reproduce, but most are harmless and in fact may even be necessary for all life, serving a useful function for the life forms around them. If their numbers are astounding then so too is their variety and most are specific to a particular kind of host organism. It's not just animal life that they target but plants, fungi, bacteria and even other viruses. Some are so incredibly small that they can hide in cells, by the millions. At the other end of the spectrum there are viruses so large that they can be mistaken for a bacterium. The largest found so far is the Mimivirus and I can't even guess as to the smallest. Some viruses can change hosts when necessary, like the cowpox virus that moved from cows to humans and became smallpox. The more we live and work around animals the more we risk exposure to new kinds of viruses. After a time we may develop an immunity to some of those viruses and although those particular viruses may not harm us we can still carry them with us when we travel and infect any strangers we meet. Viruses make more viruses by invading the cells, or cell, of another organism, commandeering that organisms genetic material to make as many viruses as is needed. So, can viruses exist without a proper host? It appears not, but what does that tell us about the Cave of Crystals virus? Are they truly alone in those pools or is there another, as yet unknown, organism present. Or is there a way for them to use other viruses as a host? Or maybe they have an incredibly long life span. Zimmer doesn't address that issue but he does cover a lot of ground, including one very special questions. Are viruses alive? Some specialist say yes, others say no and the debate has been going on since viruses were first discovered. They do seek out their specific host and invade it's cells to make more viruses, so they do have a kind of unconscious purpose. They can evolve to change hosts if necessary. They move about to find suitable environmental conditions. Sounds like life to me, but your guess is a good as mine. If the specialist don't know for sure then where does that leave the layperson reader? With plenty of reading material, that's for sure. There are other questions that occurred to me. How did viruses evolve? Were they the very first organisms or did they evolve later from from some, as yet, unknown prokaryotic bacterium that shed its unneeded genetic material for a parasitic life style? The debate goes on with no end in sight. For more on this subject and on the Mimivirus see James L. VanEtten's fine article: Giant Viruses in American Scientist July-August 2011. I had no technical or formatting problems with this Kindle edition.

LastRanger

"[Viruses are] biology's living matrix."

We share little in common with our forebears' understanding of the universe. In ancient times the earth was ensconced by a dome or firmament which held back rain and other effusions from above. Drought and wetness were tangible indicators of the pantheon's impression of earthly behavior, with a blue sky betokening the rain that lay just beyond the earth's protective shell. For many of our ancestors, the stars influenced the health of those on earth; for others, calamity and human hardship could be ascribed to nothing more than the shifting dispositions of the local deities. Maladies of the skin and throat and other physiological dysfunction were described as plagues, or instances of pestilential terror cast down as punishment. It was not until our discovery of the virus that these superordinary affiliations were shorn in favor of the vanishingly tiny world thriving right under our noses.

Viruses have been invading other life forms for billions of years with nary an invitation, yet our knowledge of this relatively young science is still fairly limited. Helming this microcosmic thrill ride is Carl Zimmer, first-place recipient of the 2012 AAAS Kavli Science Journalism competition and one of the most illustrious science reporters of our time. Author of Microcosm and Parasite Rex, pathogen science has long been his forte. In the compact A Planet of Viruses, Zimmer marshals his treasure of insights and provides us a sweeping introduction to this fascinating, if ineluctably unnerving world.

While the book is a compilation of well-connected short essays, a format that suits the material well. Each of the chapters spotlights a specific strain or type of virus which has wreaked considerable chaos on human welfare-from rhinovirus, smallpox, and influenza to HIV and West Nile virus-and Zimmer's characteristic story-centric style makes each vignette as rousing as the last. As you progress, Zimmer slowly raises the curtain on virus ingenuity, weaving accessible tales and the latest research and statistics throughout.

THE INFILTRATOR

Since viruses first breached the scientific periphery in the 19th century, over 5,000 separate strains have been identified, with possibly tens of thousands more harboring in the oceans and lining the guts of every species on earth. While they can vary broadly in physical size, shape, number of genes, and mobility within and between hosts, they all borrow from the same playbook. At the first, a virus requires a host to survive, unlike bacteria, so its blinkered priority is to gain access to the cellular machinery of other life forms. Whether it's animals and plants or bacteria and archaea, a virus does not discriminate.

I like to think of them as the world's smallest stealth agent, as resourceful as they are deadly. In what makes Ethan Hunt look like an amateur, a virus has the ability to infiltrate a host's cells in a variety of ways, a skill which amplifies as evolution takes its course. Once the virus descends upon the host's genetic structure, it can really begin its work. With full access to the genetic database the virus begins installing its own DNA onto the cells of its host, overriding the host's DNA. At this point, the virus is replicated by the host's hijacked DNA at a prodigious rate until many thousands of identical copies line the inside of the host's cells. Depending on the genetic mixture, this assimilation can disrupt a host gene's ability to make proteins, unleashing havoc on the unwitting custodian, or the virus presence can trigger the release of antibodies which scramble to shut down the intruders, subjecting the host to nasty symptoms in the process.

There is ongoing debate over whether viruses qualify as a form of life. They cannot survive outside of a host cell and are absent any kind of cellular architecture, rendering them little more than small, self-assembling clusters of nucleic acids. Even so, Zimmer is quick to point out their indispensable role in shaping and sustaining life over the aeons. "We humans are an inextricable blend of mammal and virus. Remove our virus-derived genes, and we would be unable to reproduce." (p. 93)

Viruses have also been implicated in the origin of life, as their capacity for self-replication may hold the keys to how precellular material jumpstarted the chain of life on earth. The uninvited stowaways have been shuffling genes among different host species ever since, comprising as much as 8% of the human genome. Thus not only have viruses been a tremendous force in the evolution of life on this planet, they are essential to our survival.

Zimmer also discloses plainly just how near are viruses and other infectious agents. Each of our trillions of cells can contain hundreds of viruses and bacteria. Human papillomavirus (HPV), most known for inflicting cervical cancer and killing over 270,000 women every year, is actually quite common and can be found nestled in your skin cells. We constantly shed our outermost layer of skin after cell death, depositing the virus-laden DNA all around us. That means that right now you likely have more than a few HPV viruses on the desk and laptop in front of you. Not the cheeriest thought perhaps, but you will find solace in the fact that the majority of HPV strains are benign and pose no immediate risk.

CAT, MEET MOUSE

It is true that the lion's share of known viruses introduce no changes to infected cells or simply lie dormant within our DNA. But it is also true that pathogens evolve more quickly than any known form of life. For this reason microbe trajectories always lie one step ahead of us and are difficult, if not impossible, to predict. Zimmer relates this chilling reality by describing why scientists are urging against the over-use of antibiotics. Not only do antibacterials have a null effect on viruses, they upset the delicate ecosystem inside our bodies and "incentivize" bacteria to evolve countermeasures, potentially resulting in more noxious versions of both benign and harmful strains.

In response to this dilemma, medical biologists now have their eyes on an alternative approach to fighting bacteria: phage therapy, an area in which precious little research has been conducted. Somewhat confusingly, a bacteriophage is a virus used to combat resilient bacteria. Essentially, pitting pathogen against pathogen. Zimmer tells of a lab-engineered phage (pictured below) developed by a team from Boston University and MIT that can wipe out 99.997% of E. coli strains. More impressively, "scientists at the Eliava Institute have developed a dressing for wounds that is impregnated with half a dozen different phages, capable of killing the six most common kinds of bacteria that infect skin wounds." (p. 38) Among many microbiologists, this approach to resistant bacteria is a heavily favored alternative to antibiotics. But until a wider body of research is explored, such precision warfare is confined to the lab.

EXIT: STAGE LEFT

By all accounts, the most uplifting installment is that of smallpox, which Zimmer recounts in a coda entitled "The Long Goodbye." When this dark scourge first started replicating inside of human hosts remains an open question. Telltale signs can be seen in the 3,000 year old mummified corpse of Pharaoh Ramses V, while other scientists date its emergence as early as 10,000 BC. Based on extant medical records and fatality rates, it's been estimated that smallpox caused 400,000 European deaths each year during the 18th century and another 300-500 million deaths in the 20th century alone, bringing down three empires in the process. Its final death toll across human history and its legacy in shaping civilization may never be fully realized, but it met a worthy competitor in one Edward Jenner.

Among the venerated elite in science history, Jenner used cowpox, a member of the same viral family as smallpox, to inoculate potential smallpox victims. It worked, and while Jenner did not discover the antigenic properties activated by vaccination, it was his "trial by fire" testing and scrupulous documentation of his findings that led to its widespread adoption against smallpox. In 1979, the World Health Organization declared smallpox an eradicated disease. The unflinching bravura of those who risked their lives in the global eradication effort functions as a testament to human possibility. WHO's vaccination campaigns, which achieved success largely by isolating the infected from the non-infected and administering vaccines to quarantined communities, is perhaps the greatest success story in all of medicine and lends hope for the outcome of future travails.

CLOSING THOUGHTS

Thanks to one of the finest science communicators today, the remaining essays assembled in A Planet of Viruses are every bit as informative and accessible. As stepladder to the scientific community, Zimmer has a knack for engaging readers of all stripes, from the lay reader to the armchair scientist to anyone who simply likes reading good stories. His way is precise, not overly simplified, choosing just the right level of linguistic precision to divulge this teeming underworld to his readers. While certainly not as detailed as some of his earlier expositions, this brilliant anthology serves as a perfect preamble to the bustling field of microlife. Clocking in at just under 100 pages, I highly recommend you target this one for your next free weekend, preferably before, and not after, having eaten.