Scientists have studied the way in which the Prion enters the body of mammals in order to comprehend the dangers of transmission to humans of BSE and other future TSEs that may appear. Scrapie, having been around for centuries is known to be unable to cross the species barrier to humans.
Researchers already knew that a TSE could be transmitted by feeding through their experience with Kuru, but the exact method by which the agent entered the body without being digested was uncertain. Although, the greatest incidence of Kuru was amongst women and children who were involved in the prepeartion of the food. Being primitive people, they used their hands, which were covered with cuts and grazes. It is hypothesised that abnormal prions could enter their bodies in this way and bypass the gut barrier,
The first obstacle that the Prion has to surmount is the gastric juice that contains enzymes to destroy protein, but it is known that this mechanism sometimes leeks allowing through between one in a million and one in ten million protein molecules, this is accentuated during illness or after drinking alcohol. Furthermore, abnormal PrP roteins resist this enzyme action.
The gut is the major site of contact in the body for foreign antigens. The following are all responsible for providing some form of defence mechanism.
Bacterial flora rapidly colonises gut after birth and comprises more than 1014 organisms. There are more than 400 species. Each individual flora is immunologically distinct and has a symbiotic relationship with host
Organisation of the Mucosal Immune system
Gut associated lymphoid tissue (GALT)
The gut barrier can be comprised by infection, however.
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