Nature is that lovely lady who gave us the polio virus...and the influenza virus...and the rabies virus...and the HIV virus...and so on. She's a lovely lady with death and cruelty in her eyes, and it seems she's totally committed to making all of us miserable.
In 1892, a twenty-eight year old Russian botanist named Dimitri Iosifovich Iwanowsky (1864-1920) reported in the journal of the Russian Imperial Academy of Sciences the existence of a mysterious infectious agent. He had no idea what it was, except that it was certainly invisible and passed through filters that ordinarily stopped bacteria. Was it merely a tiny bacterium? All he knew was that the agent was apparently the cause of a tobacco plant disease (tobacco mosaic disease), which made the discovery of practical importance. Tobacco, after all, brought to Europe five hundred years before, was so much a part of European culture that in any major city anywhere one could find a cluttered little tobacco shop on nearly every street corner. The Russian journal that accepted Iwanowsky's paper published in the French language, no doubt to assure notice in the academic corridors of Paris, and notice was immediately obtained. Iwanowsky, only four years out of the University of St. Petersburg, had made his mark. He also made a serious mistake by not doing further experiments to test the idea that the infectious agent was merely an extremely small bacterium--but he certainly broke new ground for others to march on.
And march they did. In 1898, the Dutch botanist Martinus Beijerinck (1851-1931), son of a tobacco dealer, discarded the idea of a bacterium as the cause of tobacco mosaic disease, proposed a "living fluid" infection, and called the agent a "virus".
No progress was made for a generation--until 20th century technology arrived. In 1935, the American biochemist Wendell Stanley (1904-1971) isolated the infectious agent of tobacco mosaic virus in crystalline form and proposed that Beijerinck's "virus" was "a molecule". Stanley's work was supported in 1936 by the Swedish chemists Inga-Britta Eriksson-Quensel (?-?) and Theodor Svedberg (1884-1971), who proposed on the basis of studies using electrophoresis and the ultra-centrifuge that the causative agent of tobacco mosaic disease was indeed not a bacterium but an agent of molecular dimensions.
A living molecule? The idea was a great puzzle in the 1930s. We now know that a virus actually consists of a small number of macromolecules, but even so, we're apparently at the interface between the physical sciences and the life sciences. Is it alive or not alive? A virus is a small assembly of macromolecules, an RNA or DNA genome plus proteins, that can replicate itself if it can get inside a compatible living cell and use the genetic machinery of that cell. A common pathological outcome is that the host cell dies after it's used for the successful replication of many virus particles. Another apparent usual outcome is that the genome of the host cell may be damaged in the replication process and turn the cell into a cancer cell.
Viruses are not our friends, and we're really only at the beginning of our understanding of what they do and how they do it. One thing is certain: if the public understood more about viruses, there might be less political and social commotion about vaccinations against viruses. This is one area where educating the public about science is in the direct public interest and not merely an enlightened abstraction. If the CDC (Centers for Disease Control) would put up billboards about viruses around the country, they might do our national security some serious good.
Readable books about viruses by experts are not plentiful enough, and the point of this essay is to recommend a recent arrival by the American virologist Michael Oldstone. In 17 chapters, the author gives the non-specialist reader a complete account of viruses and virus-caused plagues such as smallpox, yellow fever, measles, polio, hemorrhagic fever, Lassa fever, ebola, hantavirus, SARS, West Nile Virus, mad cow disease, and influenza. His final words are special:
"In the end, the splendor of human history is not in wars won, dynasties formed, or financial empires built, but in improvement of the human condition. The obliteration of diseases that impinge on our health is a regal yardstick of civilization's success, and those who accomplish that task will be among the true navigators of a brave new world."
Read this book (available now)--it's a treat.
[Michael B. Oldstone: Viruses, Plagues, and History: Past, Present, and Future. Oxford University Press, 2010.]