• Viruses are among the smallest microbes, much smaller even than bacteria.
• Viruses are not cells.
  • They consist of one or more molecules of DNA or RNA, which contain the virus's genes surrounded by a protein coat.
• Viruses can be rod-shaped, sphere-shaped, or multisided. Some look like tadpoles.
• Most viruses DO cause disease because they invade living, normal cells where the multiply and produce other viruses like themselves.
• Most viruses survive by taking over the machinery that makes a cell work.
  
  
  
  

Adapted from National Health Institute. http://www.niaid.nih.gov/publications/microbes.htm#a