Here’s an interesting link, coming to us via the one and only Bruce Schneier. Haker/maker type person Bunnie draws a fascinating analogy between influenza viruses (like our topical and quite possibly overhyped amigo, swine flu) and the computer viruses with which he is more familiar. The result? A computer geek’s guide to molecular biology…

For those not familiar with molecular biology, DNA is information-equivalent to RNA on a 1 to 1 mapping; DNA is like a program stored on disk, and RNA is like a program loaded into RAM. Upon loading DNA, a transcription occurs where “T” bases are replaced with “U” bases. Remember, each base pair specifies one of four possible symbols (A [T/U] G C), so a single base pair corresponds to 2 bits of information.

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If you thought of organisms as computers with IP addresses, each functional group of cells in the organism would be listening to the environment through its own active port. So, as port 25 maps specifically to SMTP services on a computer, port H1 maps specifically to the windpipe region on a human. Interestingly, the same port H1 maps to the intestinal tract on a bird. Thus, the same H1N1 virus will attack the respiratory system of a human, and the gut of a bird. In contrast, H5 — the variety found in H5N1, or the deadly “avian flu” — specifies the port for your inner lungs. As a result, H5N1 is much more deadly because it attacks your inner lung tissue, causing severe pneumonia. H1N1 is not as deadly because it is attacking a much more benign port that just causes you to blow your nose a lot and cough up loogies, instead of ceasing to breathe.

Researchers are still discovering more about the H5 port; the Nature article indicates that perhaps certain human mutants have lungs that do not listen on the H5 port. So, those of us with the mutation that causes lungs to ignore the H5 port would have a better chance of surviving an Avian flu infection, whereas as those of us that open port H5 on the lungs have no chance to survive make your time / all your base pairs are belong to H5N1.

So how many bits are in this instance of H1N1? The raw number of bits, by my count, is 26,022; the actual number of coding bits approximately 25,054 — I say approximately because the virus does the equivalent of self-modifying code to create two proteins out of a single gene in some places (pretty interesting stuff actually), so it’s hard to say what counts as code and what counts as incidental non-executing NOP sleds that are required for self-modifying code.

So it takes about 25 kilobits — 3.2 kbytes — of data to code for a virus that has a non-trivial chance of killing a human. This is more efficient than a computer virus, such as MyDoom, which rings in at around 22 kbytes.

It’s humbling that I could be killed by 3.2kbytes of genetic data. Then again, with 850 Mbytes of data in my genome, there’s bound to be an exploit or two.

[image by kat m research]