Thierry Heidmann’s office, adjacent to the laboratory he runs at the Institut Gustave Roussy, on the southern edge of Paris, could pass for a museum of genetic catastrophe. Files devoted to the world’s most horrifying infectious diseases fill the cabinets and line the shelves. There are thick folders for smallpox, Ebola virus, and various forms of influenza. SARS is accounted for, as are more obscure pathogens, such as feline leukemia virus, Mason-Pfizer monkey virus, and simian foamy virus, which is endemic in African apes. H.I.V., the best-known and most insidious of the viruses at work today, has its own shelf of files. The lab’s beakers, vials, and refrigerators, secured behind locked doors with double-paned windows, all teem with viruses. Heidmann, a meaty, middle-aged man with wild eyebrows and a beard heavily flecked with gray, has devoted his career to learning what viruses might tell us about AIDS and various forms of cancer. “This knowledge will help us treat terrible diseases,” he told me, nodding briefly toward his lab. “Viruses can provide answers to questions we have never even asked.”Mmmmm.... viruses....
Viruses reproduce rapidly and often with violent results, yet they are so rudimentary that many scientists don’t even consider them to be alive. A virus is nothing more than a few strands of genetic material wrapped in a package of protein—a parasite, unable to function on its own. In order to survive, it must find a cell to infect. Only then can any virus make use of its single talent, which is to take control of a host’s cellular machinery and use it to churn out thousands of copies of itself. These viruses then move from one cell to the next, transforming each new host into a factory that makes even more virus. In this way, one infected cell soon becomes billions.
Nothing—not even the Plague—has posed a more persistent threat to humanity than viral diseases: yellow fever, measles, and smallpox have been causing epidemics for thousands of years. At the end of the First World War, fifty million people died of the Spanish flu; smallpox may have killed half a billion during the twentieth century alone. Those viruses were highly infectious, yet their impact was limited by their ferocity: a virus may destroy an entire culture, but if we die it dies, too. As a result, not even smallpox possessed the evolutionary power to influence humans as a species—to alter our genetic structure. That would require an organism to insinuate itself into the critical cells we need in order to reproduce: our germ cells. Only retroviruses, which reverse the usual flow of genetic code from DNA to RNA, are capable of that. A retrovirus stores its genetic information in a single-stranded molecule of RNA, instead of the more common double-stranded DNA. When it infects a cell, the virus deploys a special enzyme, called reverse transcriptase, that enables it to copy itself and then paste its own genes into the new cell’s DNA. It then becomes part of that cell forever; when the cell divides, the virus goes with it. Scientists have long suspected that if a retrovirus happens to infect a human sperm cell or egg, which is rare, and if that embryo survives—which is rarer still—the retrovirus could take its place in the blueprint of our species, passed from mother to child, and from one generation to the next, much like a gene for eye color or asthma.
Thursday, November 29, 2007
No time to read the rest of the story now, since the whole point of getting up evilly early is to grade papers and prepare lecture, but as I ate my evilly-early-morning oatmeal for breakfast my eye did run over the opening paragraphs of Michael Specter's story in this week's New Yorker, and I must say that I cannot imagine a more alluring start to a story, it seems perfectly tailored to my interests: