London - Scientists have taken an important step forward in understanding how diseases like CJD and BSE attack their victims. They have shown that the host must be genetically equipped to allow the transport of the infectious agent to the brain, where the damage is caused. The agent that causes mad cow disease and its human equivalent, CJD, are thought to be abnormal versions of naturally occurring proteins called prions. According to the Swiss scientists, prions can only spread from the digestive system to the brain via tissue genetically capable of allowing their replication.
The prions are thought to build up in the lymphatic system before jumping across to the brain and spinal cord. It is this period of build up that causes the typically long incubation period of diseases like CJD.
Some kind of prion-expressing bridge is needed for the final jump, the researchers from the University of Zurich said. - (PA)