Tiny Terrorists

Ebola virus

If, as Nobel laureate Peter Medawar has said, a virus “is a piece of bad news wrapped in a protein,”¹⁴⁷ the world may have all the bad news it can handle with the emergence of the H5N1 virus. For more than a century, scientists have marveled at how a virus, one of the simplest, most marginal life forms, could present such a threat. “It’s on the edge of life,” explains a former director of the CDC’s viral diseases division, “between living organism and pure chemical—but it seems alive to me.”¹⁴

For a virus, less is more. Viruses are measured in millionths of a millimeter.¹⁴⁹ As one writer described them, “Like tiny terrorists, viruses travel light, switch identity easily and pursue their goals with deadly determination.”¹⁵⁰

Viruses are simply pieces of genetic material, DNA or RNA, enclosed in a protective coat. As such, they face three challenges. First, they have genes, but no way to reproduce, so they must take over a living cell and parasitically hijack its molecular machinery for reproduction and energy production. The second problem viruses face is how to spread from one host to another. If the virus is too passive, it may not spread during the host’s natural lifespan and thus will be buried with its host. The virus must not be too virulent, though. If a virus comes on too strong, it may kill its host before it has a chance to infect others, in which case the virus will also perish. Finally, all viruses need to be able to evade the host’s defenses. Different viruses have found different strategies to accomplish each of these tasks.¹⁵¹