Читать книгу Principles of Virology - Jane Flint, S. Jane Flint - Страница 26

Despite the appalling statistics from human and agricultural epidemics, it is important to realize that viruses can also be beneficial. Such benefit can be seen most clearly in the marine ecosystem, where virus particles are the most abundant biological entities (Box 1.1). Indeed, they comprise 94% of all nucleic acid-containing particles in the oceans and are 15 times more abundant than Bacteria and Archaea. Viral infections in the ocean kill 20 to 40% of marine microbes daily, converting these living organisms into particulate matter. In so doing they release essential nutrients that supply phytoplankton at the bottom of the ocean’s food chain, as well as carbon dioxide and other gases that affect the climate of the earth. Pathogens can also influence one another: infection by one virus can have an ameliorating effect on the pathogenesis of a second virus or even bacteria. For example, mice latently infected with some murine herpesviruses are resistant to infection with the bacterial pathogens Listeria monocytogenes and Yersinia pestis. The idea that viruses are solely agents of disease is giving way to an appreciation of their positive, even necessary, effects, and a realization that their unique properties can actually be harnessed for human benefit (Volume II, Chapter 9).