Wednesday, September 05, 2007

Creationists Know Everything: Part Deux

Why is it, that when youre having a *conversation* with a Creationist, they dont 'ask' you about your area of expertise, they 'tell' you?

Ian and I are being schooled on genetics and virology over in the comments of Another savage blow to my Behe critique. Though Creationists were unaware of the existence or significance of HIV-1s Vpu gene, we are now learning from PaV that the evolution of Vpu doesnt count because SIVcpz got Vpu from influenza.

Minor problem.

Thats impossible.

Not that that will stop a Creationist:

If someone has the flu, wouldn't you expect their T-cells to attack the flu? So, if the T-cell with the HIV attached comes into contact with cells in the airway that contain the flu virus (and, it so happens, that the genes of Type A Influenza are all single RNA strands, i.e., independent of each other) we now have the round hole touching up against the square peg.
Heres the deal-- thats a good try for a non-biologist trying to explain something he/she doesnt understand. Though I think it takes a *special* kind of arrogance to tell a virologist about virology, its a good try. But its wrong. And we're going to use it as an opportunity to learn more about virology and the immune system. HAHAHAHAHA! I TRICKED YOU! You thought you were going to get another Creationist Bashing post, and now youre going to LEARN!! HAHAHA Too late to stop reading, now! AHAHAHA!


First, the immunology. The T-cells that would come into contact with infected epithelial cells are called cytotoxic T-cells. They dont so much 'kill' infected cells, as 'persuade them to commit suicide*.'

The target of HIV-1 is helper T-cells. Helper T-cells have specific a receptor HIV-1 needs to infect a cell-- CD4 (plus some co-receptors, but thats neither here nor there). Thats why HIV-1 doesnt infect your liver cells, or neurons-- they dont have CD4. Helper T-cells will not come into contact with cells infected with influenza because epithelial cells dont have MHC Class II.

Even if they did, influenza could not get into helper T-cells. Like HIV-1 and CD4, influenza requires a very specific lock for its key.

Onto the virology. Lets pretend by some mode of magic, influenza and HIV-1 infected the same cell. They would never see one another.

Influenza enters your cells through endocytosis. A pH change in the endosome causes the virus to release its negative sense RNA into the cytoplasm. Using RNA dependent RNA polymerase, it makes its message in the cytoplasm, and gets the hell out of Dodge.

Influenza is a hit and run virus.

HIV-1, on the other hand, enters your cells through fusion with your cell membranes. When it uncoats, it uses reverse transcriptase to create DNA which is taken to the cell nucleus and integrated into your DNA. Then, it either transcibes its message in the cell nucleus to make some friends, or it just sits there-- silent.

HIV-1 is a hit and stick virus.

But lets do some more pretending. Lets pretend they DID meet! What would happen?

Well, what would a retrovirus do with a negative strand RNA virus? RT doesnt just start reverse transcribing any piece of RNA it comes upon. Its an insane process that requires specific sequences at specific sites to work. Theres just no way HIV-1 could steal a gene from influenza.

But wait! Creationist comes this close to asking a question!!
And, IIRC, HIV is known to incorporate genes from one subtype into the other, so why can't it incorporate the single gene strand for the M2 protein.
AWWW!! So close! It would have been a good question if he/she had asked it instead of phrasing a question like its a fact!!!

How do Subtypes recombine? Superinfection! A person is infected with HIV-1 subtype A and HIV-1 Subtype B. Both viruses manage to infect the same cell (though HIV-1 tries to prevent superinfection, it happens, and I see it in my own experiments). Now remember, there are TWO copies of the HIV genome in each virus-- so if you have a superinfection, you can package one Subtype A and one Subtype B into a virion. Okay, all those hops in the animation above? Both of the packaged genomes have the *right* signals and sequences, so RT can hop from one HIV genome to the second copy, and then you get a Subtype A/B virus.



* This joke comes to you from Immunology!


Chris Harrison said...

I think you might have confused PvM for PaV. PvM's a good guy!

ERV said...

DANGIT! I knew I would do that. We're now even hehe!

olegt said...

Curtain call for PaV.

Tyler DiPietro said...

It's a beautiful thing to watch experts debunk cranks. I can't wait to see where the goalposts are gonna move this time.

Ian Musgrave said...

Ian and I are being schooled on genetics and virology over in the comments of Another savage blow to my Behe critique.

And ion channel structure and function, the thing I did my postdoc on. I'm not Ron Lucas (but I do have some alpha7 nictotinic channel transfected cell lines courtesy of Ron), but I do know my way around ion channels (and was even very briefly and very marginally involved in the hunt for the TRP channel gene). Anyway, I've done the sequence alignments, lets see if PaV accepts that evidence.

Israel Barrantes said...

Really stupid. Negative (antisense) and positive strand RNA viruses never recombine with each other even when they could be in the same cell -which is a very unlikely event, by the way. Let's send these guys back to school.

ERV said...

Ian-- I didnt know you played with ion channels! I miss ion channels! I got to learn a lot about them in undergrad (surprisingly) through all my neuro and pharmacology courses!

Israel-- Like I told quantok, Creationists know everything. The rest of us are just trying to catch up.

Oleg-- I dont think PaV is coming back. He/She has an answer that quiets their cognitive dissonance, they're done. Though PaV is of course still welcome-- he/she has good questions, if he/she would ask them.

olegt said...


This looks like an opportunity for another teaching moment.

ERV said...

Ill cut it up if you all reeeeally want :) But I think Tyler did a great job, and I think its important that a layman, in no biological field whatsoever, got my post enough to respond to Luskin.

Tyler also had a nice post up about Sal.

hehehehehehe :)

olegt said...


I think Casey deserves some spanking from you personally. He was a naughty boy today.