Viruses leave traces for long after infection
Viruses do not always kill the cells they infect. Researchers at the University of Basel have discovered in experiments with mice that cells have the power to self-heal and eliminate viruses. However, these cells undergo long-term changes. The findings may provide a hint as to why cured hepatitis C patients are more susceptible to liver cancer for years after.
Viruses need the infrastructure of the body’s cells in order to multiply. With many types of viruses, this ultimately means death for the affected cell if its membrane dissolves and the newly created viruses swarm out to attack new cells. But some viruses do not kill the cells they infect – presumably with the aim of maintaining the infection for as long as possible. These include hepatitis B and C viruses, which cause chronic infections in humans.
Until now, it was generally assumed that such viruses remain permanently in the infected cells of the body. However, a research team led by Professor Daniel Pinschewer from the University of Basel now reports in the Journal of Experimental Medicine that this is not the case. Their experiments involved a mouse virus called lymphocytic choriomeningitis virus (LCMV), which triggers a chronic infection in mice – similar to hepatitis C virus in humans – and also infects the liver.
Virus eliminated, but not without trace
This model enabled the researchers to demonstrate that the virus disappears from the infected liver cells after a certain time period. It is not yet clear exactly how this happens. However, the researchers were able to rule out the possibility that the cells need the support of immune cells in order to do this. “Liver cells seem to have their own mechanism for removing a virus from within,” says Dr Peter Reuther, one of the study’s two lead authors. The chronic infection by such viruses is based on a continuous infection of new cells.