Over the last few decades many tests have performed on infected
brain matter, first from scrapie
cases, then cases of BSE, CJD
and other recent TSEs, scanning it
with every known method for remnants of bacteria, a virus or any
other known infective agent; but
to no avail. The only tests that showed any consistent differences
between samples of diseased and unaffected brain were screenings
by gel electrophoresis,
first performed by the scientist David Bolton. When the results
were developed a thick band was present in the readings for each
of the samples of diseased brain, and absent from those of the
healthy samples. This signaled the presence of a different form
of protein that had to be associated with the disease, and it
was always found to be only present in TSE
affected brain whenever the procedure was repeated. This protein
has since been identified as PrPsc,
or the Prion.
When first announced, the idea that a protein could be the sole
agent of a disease was viewed as scientific heresy, as it was
a cardinal rule of biology that reproduction of any form requires
Nucleic Acid (NA) in order for the hereditary characteristics
of the species / strain to be handed
on; this applied for everything from the grandest mammal to the
lowliest virus or bacteria. The protein as put forward contained
no form of NA, and yet reproduction was clearly taking place.
Steadily though, in the absence of evidence of any other agent,
support has steadily grown among the scientific community for
the Prion Theory; although there
is still no concrete proof whether it is the actual agent
of the TSEs, or simply a byproduct
of the TSE diseases.
A second, though much more marginal theory is that the agent
of TSEs is an organism called a Virino,
a smaller version of a virus composed of simple RNA for the genetic
information, surrounded by a tough shell of protein.
