Before I start talking about endogenous retroviruses, there is one thing I need to make clear about exogenous retroviruses first, for anyone who deals with pseudoscientists.
When dealing with Creationists/Deniers on the topic of virology, almost immediately you will be confronted with a form of ‘viruses are magic’. For instance, Professional HIV Denier Rebecca ‘Blondie’ Culshaw is just certain that HIV-1 is really a harmless ERV (see points 1-17), and Creationists routinely pull ‘scientific facts’ about ERVs out of thin air.
So I really cant stress this one point enough:
Okay, you all know that a retroviruses are viruses that go ‘backwards’, genetically. Instead of going DNA–>RNA–>Protein, they go RNA–>DNA–>RNA–>Protein. While its easy to lump all ‘retroviruses’ into a homogeneous group, its important to remember that retroviruses are actually an extremely diverse family.
To say ‘HIV-1 is the same as Rouse Sarcoma Virus is the same as Mouse Mammary Tumor Virus. Theyre all retroviruses!’ is as silly as saying ‘Humans are the same as blue whales are the same as fruit bats. Theyre all mammals!’
There are currently seven types of retroviruses, with their own defining genes (simple? complex? lots of bells and whistles?), methods of virus assembly (cytoplasm? cell surface? trafficked through the ER?), viral structure (cone? cylinder? sphere? spikes? sugars?), desired host cells (dividing cells? terminally differentiated?), etc.
But what all of these guys have in common is their need for the genes gag, pol, and env (which I will be discussing more at a later date), genes we can sometimes find hanging out in our DNA as endogenous retroviruses:
- Alpharetroviruses– Can be ERVs
- Betaretrviruses– Most ERVs
- Gammaretroviruses– Can be ERVs
- Deltaretroviruses– No ERVs
- Epsilonviruses– No ERVs
- Lentiviruses– We have found *one* lentiviral ERV
- Spumaviruses– Can be ERVs, but the endogenous versions are only distantly related to current-day, exogenous spumaviruses
So in future posts when Im talking about ERVs, or when you are dealing with a pseudoscientist talking about ERVs, remember we arent just playing Bible-code games. We know what group the ERV in question used to belong to. We can trace how that ERV mutated differentially in different species of primates, or notice its only found in humans, or that its only found in chickens. We can know the ERV in question isnt coding for HIV-1.
If your pseudoscientist friend says something that sounds like magic– “Well maybe HIV-1 is an ERV that got a functional envelope gene from influenza cause you had the flu and were huffing poppers!”– Dont stand for it. Say “Retroviruses are not magic. Show me the evidence for that claim.”
And, if you want to learn more about retroviruses (I mean beyond Wikipedia, but not quit ‘IM GONNA GO BUY A TEXTBOOK!’), Cold Spring Harbor has a book on retroviruses online, for free!! Its ‘advanced’ reading, but if this topic interests you, you can get through it. Or if you get stuck, leave me a Q in the comments or drop me an email ?