Prion diseases hide out in the spleen!!

Since we are going to be looking at prions, which are composed of misfolded forms of a protein called PrP, later on, I thought that this study presented an interesting set of facts regarding recent discoveries made about prion diseases.
It was recently found that Prion diseases such as bovine spongiform encephalopathy (BSE) and variant Creutzfeldt–Jakob disease (vCJD) are able to jump across species much more easily than previously thought; in fact, it seems that they can start replicating in the spleen without necessarily affecting the brain. This would mean that thousands of people could be silent carriers of a prion infection and not realize it! It also increases the risk of transmission of the prion infection to more people through surgery, organ donations or blood transfusions.
This also relates back to the question that we had in our problem set this week - do prions have a wide host range and is that why they are able to jump from one species to another easily, according to this new study? Is that why they are called the "barrier breakers"? Apparently, these pathogenic agents are not only able to replicate in the brain, but can also affect lymphoid tissue, such as the spleen, tonsils and appendix. Do these findings match the original assumption that species barriers are very difficult to cross?

- Julie