I was reading a blog I sometimes frequent, called slatestarcodex, authored by a rather polymathic psychiatrist who has some background in conworlding (which the context in which I first came across him).
He mentioned in one of his collections of links a concept I hadn't come across before, which is the idea of "cell line infections." Since this was clearly related to cancer, and I've become a bit of a glutton for semi-hypochondrial cancer-related online reading, I followed the link and satisfied my curiosity.
Here is the article. I also did some reading in wikipedia.
Cell line infections are scary. The idea is that a given cancer can "evolve" sufficiently that it can be transmitted like other infections vectors – e.g. bacteria or viruses or prions – to other individuals. There are now documented CLIs for dogs, clams, and tasmanian devils (and in the last case, it may be contributing to the rapid extinction of the species). Basically, the idea is that my cancer could end up in your body, and take root there and become your cancer. Infectious cancer. More fun.
From a biological perspective, these cell line infections are weird. These are things that behave, for all intents and purposes, like single-celled parasitic organisms, not unlike infectious bacteria. Yet genetically they are your relatives (well, they are the relatives of the particular individual in whom they first arose). To anthropomorphize a bit, they know you. In the documented instance, the dog CLI knows how to deal with a dog immune system, for example – because it is, in a genetic sense, just a weird manifestation of an actual dog – a sort of single-celled vector of a dog.
Apparently, there is something similar in the always-wacky insect world, among what are called parasitoid wasps. These wasps' eggs and larvae (implanted in other insect species' larvae) send out single-celled vectors called teratocytes that manipulate the host individuals' metabolisms to make it a friendlier environment for the growing eggs. This is not the same as e.g. the infamous toxoplasmosis, which is a case of a kind of mutualistic/parasitic symbiosis between a single-celled organism and several multicelled organisms. Instead, these teratocyte vectors sent out by the wasps are members of the same wasp species, genetically – just a kind of strange phenotype.
So following on that insect-related terminology, maybe these mammalian cell line infections could be called "rogue mammalian teratocytes."
Just when one feels one has a handle on what is biologically possible, something comes along that makes it all seem quite ephemeral, and ungraspable – the cohesive theoretic picture melts into a swirling, incoherent field of possibilities, like a poorly-realized science fiction novel.
[daily log: walking, 7 km]