Viral Hepatitis Complications

Humans suffer from several different viral infections causing hepatitis that can sometimes result in long-term complications (chronic active liver damage, cirrhosis and hepatocellular carcinoma). Hepatitis viruses B and C (HBV and HCV) are highly infectious blood-borne viruses that infect millions of people world-wide. Following both infections, a significant proportion of infected humans suffer chronic hepatitis and long-term complications. Chimpanzees can be infected with these viruses, both naturally in the wild, and experimentally in the laboratory. Both HBV and HCV successfully infect and replicate in chimpanzees. However, neither virus seems to cause as high a frequency of long-term complications as is seen in humans. Interestingly, the later liver damage in chronic hepatitis is thought not to be due to the virus per se, but due to the excessive host T cell response to it. In this regard, there is evidence that human T cells are more reactive than those of the chimpanzee. Of course, the experimental infection of chimpanzees with large doses of virus does not mirror what happens in natural human infections. The initial events could also affect the eventual immune response to the virus.