26 September 2013
How do we get sick? Let’s make a list…
- Genetic disorders; those we inherit from our parents
- Environmental issues (obesity, diabetes)
- Infection by bacteria
- Infection by fungi
- Infection by viruses
- Infection by animals (tapeworms, etc.)
- Infection by protozoans (ameobae, dysentery, etc.)
- Infection by carcinogenic cells (e.g. Tasmanian devil contagious mouth cancers)
That last one may sound pretty weird, but today’s book is about a weirder one:
- Infection by proteins
Infectious proteins, dubbed prions by a leading researcher, are at the root of a host of odd, terrifying diseases. Mad cow disease is probably the most familiar of these, although the farmers among you may have heard of a related condition in sheep (“scrapie”) or in wild ungulates (“chronic wasting disease”). People can get kuru if they are New Guinea cannibals, or Creutzfeldt–Jakob disease, or fatal familial insomnia, if they are unfortunate enough to be born into an Italian family with a genetic predisposition to that horrific condition. From onset to death, an agonizing 15 months transpire, during which physical and cognitive ability decline in uncontrollable, incurable progression… Their brains end up riddled with holes, they lose the ability to sleep, they release adrenaline like they are running from wolves, they sweat profusely, they burn themselves out. The spongiform encephalopathy (holes in the brain) is a consistent characteristic among mammalian prion diseases.
The book profiles different prion diseases over time, in people and in non-human animals, and goes deep into the character of the scientists who research them (boosterism, pedophilia, and injurious academic egos all have a place in their collective saga). I found it absolutely fascinating, quite well written (D.T. Max also wrote a biography of David Foster Wallace, so he knows a good turn of phrase or two), and also quite terrifying.
The thought that’s so terrifying? A pathogen that cannot be killed? Bleach doesn’t kill prions, because they are not alive. You can’t treat prions with antibiotics or gene therapy. They just… are. There’s no cell membrane, no peptidoglycan, no DNA or RNA. Just a small protein, a little folded-up length of amino acids that will mess up your body if it gets in. Fields infected with scrapie hundreds of years ago still infect sheep today.
How do these proteins do it? There are a couple of possibilities:
- They interact with a gene on a chromosome, causing it to be expressed, that produces more copies of the same protein.
- They interact directly with an otherwise innocuous protein, causing it to re-conform into a new, injurious shape. This refolded protein repeats the cycle, and a cascade ensues.
I really enjoyed the book, in spite of its macabre subject matter and my own ensuing distrust of eating meat. I eat both venison and beef, and the possibility of being infected with a mammalian spongiform encephalopathy is enough to put me off both….