What neat evolutionary tales do you have for us this week, HIV-1 Vpu?
We discovered a while back that we have a whole ‘new’ component to our innate immune system we didnt know existed until we started to investigate the peculiar mutation rates within HIV-1 Vpu. This protein is called ‘tetherin’, and every cell in your body (not just your immune cells) make it in response to some viral infections. The result of this, is that progeny virions are ‘tethered’ to the surface of infected cells. Theyre trapped. Cant float off and infect someone else.
Well, HIV-1 Vpu has been mutating wildly in humans. Like, HIV-1 Env mutates a lot, but its under pressure from their hosts antibodies. Vpu mutated more than Env. Whats going on? Turns out Vpu was mutating in response to human tetherin, as one of Vpus ‘jobs’ is to degrade tetherin, thus freeing the babby viruses.
However, HIV-2 also downregulates tetherin in infected cells, even though HIV-2 does not have a Vpu protein. This makes sense, as HIV-2 has to ‘deal’ with tetherin as much as HIV-1. Creationists have latched onto this fact as ‘evidence’ Vpu ‘isnt really new or all that special in the first place’, or as Behe calls it ‘insignificant’. “Bawwwww, bot dem der HIVs do deh same things! Aint be nuttin ebolbing!”
Yes, HIV-2 also has a mechanism for downregulating tetherin. Its HIV-2s envelope protein that does it, since it has no Vpu. What happens, is, in HIV-2 infected cells, tetherin is downregulated at the cell membrane, but it is still upregulated in the cell as a whole as the cells normal response to viral infection. With HIV-1 and Vpu, tetherin is globally downregulated.
Evolution created two entirely different mechanisms, two entirely different solutions, to the exact same problem.
To quote Dembski/Marks totally super peer reviewed paper:
“The key contention of ID is that design in nature, and in biology in particular, is detectable. Evolutionary informatics, by looking at the probability requirements* of evolutionary processes, points to probability* sources beyond evolution and thus, indirectly, to a designer.”
When Dembski and Behe bawww about the ‘probability of X evolving’, or the ‘probability of Y evolving’, there is no reason why X or Y needs to evolve, even if it already did. A might have been a perfectly ‘right’ answer. And B. And C. And D… Hell, E might have been the ‘best’ answer to the problem, but HIV-1 stumbled into X first, so there it is.
We know HIV-1 and 2 have figured out two independent solutions to the same problem, tetherin. Apparently, lots of other viruses have too (other retroviruses, ebola, etc). So how can you look at Feature X and proclaim ‘Feature X is so exquisiteee! Its so very impossible to eeevolve! This amino acid change, that, eet does nut work! Design! Design!’, when Feature X never had to evolve the way it did in the first place, and you have no friggen idea how many roads lead to Rome? This is another example of what I was getting at in this post.
Its random, and not random, and its very pretty. Quasispecies, chaos, order, its peaceful. I dont know why Creationists are so disturbed by it.
* Dembski calls probability ‘active information’ and ‘informational requirements’ for some reason. I have been advised ‘not to play his rhetorical games’ and to call those terms probabilities, so there ya go.