United Press International, April 23, 2007 GALVESTON, Texas, April 23 (UPI)-U.S. scientists have found the dissimilar hepatitis A and C viruses attack the same protein to block the body's immune defenses. Despite both infecting the liver, the two viruses are far apart genetically, are transmitted differently and produce very different diseases. Hepatitis A spreads through the consumption of fecal particles from an infected person, while hepatitis C is generally transmitted only by direct contact with infected blood. But researchers at the University of Texas Medical Branch at Galveston have found the two viruses both avoid destruction by the immune system by attacking the same protein.