Steps in Replication
Modern Vaccine Strategies
Our Defences Against Viruses
In the struggle of human beings, animals, and plants to survive and reproduce, the diseases caused by microbial parasites are a considerable burden. For complex animals and plants to thrive, they have had to devote a significant percentage of their genetic information and their energies to erecting defenses to neutralize or kill microorganisms. Human beings have developed physical barriers(skin, for example) and synthesize enzymes that attack and degrade bacteria-- our tears, for instance, contain such an enzyme. We have specialized cells, the macrophages, that are attracted to bacteria, engulf them, and kill them(phagocytize them). Chief among our defenses, however, is the immune response to foreign organisms. Without the immune system, we could not live in the sea of microorganisms that surrounds us.
In general, antibodies protect us against many viruses as well as some bacteria, where they bind to the cell surface and help macrophages digest the bacteria.