Description This electron micrograph shows an H1N1 influenza virus that causes disease in pigs. It is magnified 37,800 times. Several virus particles are developing while being grown in chicken eggs. Credit Public domain/ Centers for Disease Control and Prevention/ Dr. E. Palmer and R.E. Bates, content providers/ 1976 Source http://phil.cdc.gov/phil/imageidsearch.asp (Image ID # 10143)