[restalis]

Yes, it can not be "killed" but, as other dangerous/infectious particles (like viruses), it can be destroyed. The immune system is able to naturally develop defenses against both live and inert foreign bodies, but only if the given body is over a certain size. The small objects (relative to cell size) do not trigger antibody creation and that is why this abnormally folded protein is so dangerous. There are, however, methods in which the organism is trained to recognize and develop natural defenses against bodies as small as a molecule, say, to prevent relapse in drug addicts:

http://www.doctortipster.com/11968-new-vaccine-against-metha...

http://www.livescience.com/21132-cocaine-vaccine-cure-addict...

http://www.voanews.com/content/scientists-develop-experiment...

This method may be a little bit costly (relative to promised returns of solving a problem that does not directly affect humans) and with limited effect, but still, it may be a way worth investigating.