Friday, November 10, 2006

Cylon Killing Virus

If you are following Battlestar Galactica, you know that a Cylon ship searching for Earth found an ancient space beacon, possibly left behind by the 13th tribe from Kobol. The probe carried a plague that killed almost all the Cylons that came into contact with it, and apparently has the potential to survive the process of "resurrection", in which the consciousness of a dying Cylon is transferred to a new body. In tonight's episode, Doc Cottle analyzes the disease and finds it is caused by a virus:
I identified the virus. We know it as lymphocytic encephalitis*. The disease is carried by rodents, rats mostly. But a couple of hundred years ago, humans developed an immunity.
* I'm sure Doc Cottle really mean lymphocytic encephalitis virus, since encephalitis is the disease. Of course the doctor's description leaves a few questions.

What's an encephalitis virus?

Encephalitis refers to brain inflammation that is usually caused by viral infection. There are several types of viruses that cause encephalitis in humans. The arenavirus Lymphocytic Choriomeningitis Virus (LCMV) is carried by rodents, can be transmitted to humans and causes both meningitis and encephalitis. So far, so good.

The biological basis of the humanoid Cylons hasn't been explained. According to an infected Simon Cylon, the infection affects their electrical systems.
They told us . . . that there was a bio-electric feedback compoent to the pathogen. It corrupts how our brains manage our immune systems.
While that may be plausible, I still can't figure out how the virus might be sent along with the Cylon consciousness to the "Resurrection Ship".

Could a virus remain infectious for thousands of years?

While some viruses can only live a few hours or days outside of an animal host, in 1999 tomato mosaic virus was found in 500-140,000 year old ice in Antarctica with its RNA intact. If the virus has a tough protein coat, it might survive in the frozen wastes of space for just as long.

Could humans become immune to a particular virus over the course of a few hundred or thousand years?

That the entire human population could evolve immunity over such a short period seems unlikely to me. For example, here on Earth evolutionary pressure by malaria is strong, but immunity is not universal, even in exposed populations. Now imagine a population spread over 12 separate planets, with the technology for both effective rodent population control and the development of antiviral agents. Such rapid evolution seems even less likely under those circumstances.

Perhaps the 12 Colonies used some sort of anti-viral gene therapy?

Battlestar Galactica is really about the interactions of the characters, and science is secondary. You have to suspend disbelief and accept things like consciousness-transmission (not to mention virus transmission) through space. I don't let scientific inaccuracy get in the way of my enjoyment of the show.

At the end of the episode, it's revealed that the virus was an exact match to one reported "over 3,000 years ago", about the time the 13th tribe left Kobol. It looks like the colonists are on the right track for Earth!

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Anonymous said...

While the virus cannot be transferred to the resurrection ship, perhaps the corrupted Cylon mind is transferred intact, and that's what damages the Cylon systems.

Peggy said...

That's a possible explanation.

Also, my husband pointed out that we only have the speculation of the Cylons that the virus could be spread via resurrection. It's possible that the Cylons were wrong.

Jesse said...

Well, we can make a safe presumption that Cylon brains are biochemical. After all, "skinjobs" are supposed to be ridiculously difficult to detect, which would not be the case if their skulls were full of silicon and metal. Assuming that those brains hold knowledge and personality as they do in humans, this will also be biochemical in nature.

While we don't know the method of transference behind Cylon resurrection, it's reasonable to infer that the new bodies undergo a process that "writes" a stored backup scan to the biochemical structure of the new blank brain. Given this, it's entirely reasonable that the copying process might replicate any viruses (which are just bundles of RNA in a protein shell) that are included in the brain-backup scan.

Also possible are prionic diseases such as bovine spongiform encephalitis, or "mad cow". Prions are not viruses per se, but protein structures normally found in the nervous systems of mammals that have become malformed. This malformation replicates upon contact with the standard protein structure, resulting in long chains of these twisted proteins slicing their way through tender brain tissue. Our immune systems ignore prions, since they are chemically almost identical to the proteins that should be present. So even if the Cylon backup/restore system screens out viruses, it might let prions through.

This would also explain the rapidity of the diseases spread. Prions only spread through direct contact with infected nervous tissue. On earth, such contact is restricted to eating that tissue. But Cylons appear to interface via troughs of goo, which certainly implies a biochemical interaction directly to their nervous system.

On the other hand, humans can't really become immune to prions, and unless they had their own goo-trough interfaces 3000 years ago (or were brain-eating cannibals) such diseases wouldn't spread among them anyway. Prionic diseases also take months or years to develop symptoms in Earthly biology, whereas the Cylon affliction seemed to strike within hours of exposure. But it's still an intriguing possibility.

Peggy said...

Jesse: That's an interesting hypothesis. The only problem is that it appears to be spread via casual contact, not just goo, and Doc Cottle actually said it was a form of encephalitis. I like the idea of infecting or contaminating the cylon's goo system, though.

Here's another question: if resurrection of a sick cylon can spread the disease, what happens when an immune cylon is resurrected? After Helo's Sharon (Athena) was exposed to the virus, Doc Cottle examined her and found her immune too - maybe from antibodies from her hybrid baby. In the last episode, Athena died and was resurrected on the cylon ship - does that mean she actually helped give that ship's crew immunity?

Jesse said...

"Encephalitis" is just a condition; "encephalo-" = brain and "-itis" = inflammation. Inflamed brain tissue = encephalitis, regardless of what caused it.

What reason do we have to believe it's spread by casual contact? If I recall correctly, only the one basestar that brought the probe aboard was infected. Once the virus/prion/whatever system was contaminated (possibly by some gooey method of analyzing the probe), all Cylons on the ship would get it as they plugged in to... communicate, or recharge, or add some music to their cyPod, or browse for hot pictures of appliances. I dunno.

I forgot about Sharon's immunity, and that more than anything else says my prion idea is wrong. For an immunity to pass to the mother it must be part of the immune system (as opposed to something structural such as blood cells shaped in a way that makes malaria leave them alone). Immune systems do not, as far as I know, do a darn thing about prions.

As for whether or not the immunity would be shared... interesting question. If my theory about biochemical brain scanning/copying is correct, than not necessarily. The new Sharon would probably be immune, since the blood in her brain (if it's copied as well) function like a vaccine made out of someone else's blood. The absence of scars on new copies argues that only specific details are copied from old to new, and the rest is left/recreated as per the universal template. Whether or not Sharon could share this immunity depends on whether the resurrection process or goo-interface process are smart enough to deliberately gather and share auto-immune information. Pathogens spread by themselves (pretty much by definition), but immune systems are a little less eager to reproduce with out some external encouragement.

Peggy said...

Honestly, I had assumed infection-via-contact for two reasons: it seemed the most likely way of spreading the disease from the probe (it's a human probe, so I thought the goo-interface unlikely), and because Doc Cottle seemed to think so (and he does explicitly say it's a virus that is usually carried by rats). You are right, though, there is no evidence presented one way or the other.

As for the resurrection, it seemed most likely to me that the physical body is a general template, unique to the model and the "memories" of the dead cylon are wirelessly transmitted to the ship where the resurrection takes place, and those memories are subsequently imprinted on the "blank" brain template (rather than a Star Trek-type rematerialization). We've seen that the memories can be stored electronically, as when they decided to "shelve" the Number 3/D'anna. For the infection to be passed via resurrection, the virus would have to have been encoded among the memories.

I think it's possible that this is something that is feared by the Cylons (who have shown to be superstitious) but may not be a reality.

Anonymous said...

With the particular virus they alluded too, it would be hard to explain how it would be transferred to the resurrection ship. However, certain viruses (such as HIV) incorporate their genetic material into the host DNA becoming a provirus. You could make a small leap to say that this change to cylon dna could be the code that is downloaded to the mothership, thus spreading the virus.