Sunday, March 1, 2009

Prions and Science

Representative virus-like arrays of 25-nm particles

Non-scientists are sometimes surprised to find how open-minded science actually is. There is room for everyone - with the slight caveat that if you are going to do science you need to do it in a scientific way.

So, for example, I mentioned that although the majority of scientists now accept the prion hypothesis for diseases like Kuru, CJD and BSE, there are still a few who do not. Science is not a democracy - we don't vote for a favorite hypothesis and then make everyone accept the conclusion. Rather, one of the strengths of science is that there will always be people who are testing hypotheses even after most people accept them. This is a good thing because it either strengthens the evidence for the existing hypothesis or leads to a new, and better, one.

One of the prion hypothesis skeptics is Laura Manuelidis, a professor of neurobiology at Yale University Medical School. She believes that the prion proteins are not infectious, but are a pathological result of an infectious virus binding to this host protein. Two years ago she published a paper in the prestigious journal Proceedings of the National Academy of Sciences, Cells infected with scrapie and Creutzfeldt–Jakob disease agents produce intracellular 25-nm virus-like particles, which describes, as the title suggests, the discovery of virus-like particles in the brain tissue of animals infected with so-called prion diseases.

There is a newspaper article about her work which provides a popular summary and some response to her PNAS paper:

Neurobiologist Kamel Khalili said he has seen the electron microscopy images from the new paper and the particles certainly look like viruses.

There is a large body of evidence supporting the prion theory, albeit circumstantial, he said. "We must always keep our minds open," said Khalili, chief of neuroscience at Temple University School of Medicine.

1 comment:

Rachel Jones said...

I think it's pretty cool that we're living through this period of time when scientists are trying to figure out what prions are/how they work/if they exist. (Well, it's not cool that a lethal disease exists, but that this is the history-making time.)

This entry reminded me of when we learned about the Germ Theory in class. Even when the supporters of the Germ Theory were accumulating more and more evidence to support it, the Miasma supporters were still trying to test and prove the Miasma theory.