gp120 glycoprotein for HIV

[mortonman1]

Hi,

This is my first post. I have practically no background in bio but I am very interested in pursuing it as a major-- i'm only in high school. I am very interested and curious about immunology.

heres my question: I got this from wikipedia.... Since CD4 receptor binding is the most obvious step in HIV infection, gp120 was among the first targets of HIV vaccine research. Efforts to develop HIV vaccines targeting gp120, however, have been hampered by the chemical and structural properties of gp120, which make it difficult for antibodies to bind to it. gp120 can also easily be shed from the surface of the virus and captured by T cells due to its loose binding with gp41. A conserved region in the gp120 glycoprotein that is involved in the metastable attachment of gp120 to CD4 has now been identified and targeting of invariant region has been achieved with a broadly neutralising antibody, b12.

 

Since gp120 is diffficult to bind to, why cant they genetically engineer effector cells to produce the antigen receptor for gp120? also, what about it chemical composition makes it so hard to bind to?

 

also, how many variations of CD proteins can a glycoprotein for a pathogen have? i was wondering because people say that HIV mutates so that its practically impossible to create a vaccine, so how many different glycoproteins can it make? 10^10???

 

lastly, whats the difference between a MHC protein and a CD protein?

Thanks a lot for any answers i get. its appreciated.

[Greippi]

I always assumed the reason why targeting the gp120 never worked was because of the extremely high mutation rate - by the time you've worked out a vaccine against one type of it, it has mutated so it's completely different and the vaccine is no use. I also assume the paper referenced in that wikipedia article is work in progress (the targeting of the invariant region).

 

CD proteins are found on white blood cells, MHC class 1 proteins are present on all nucleated cells, and class 2 on antigen-presenting cells. MHC present antigen to T cells.

[mortonman1]

Ya i understand that it mutates, i think i mentioned that, but that's what i don't quite understand. I guess the pathogen, in this case HIV, is unaffected by the CD protein it has? so when it mutates it doesn't affect the process that the HIV virus undergoes to stay alive. Thats strange. How does it even mutate? Does DNA Polymerase and Rna polymerase purposefully allow mutations for the glycoproteins?

[Greippi]

The mutations don't change what protein it has. It's still the same protein, just subtly different. Different enough to stop the immune system recognizing it for a second time/for a vaccine to be effective against it.

 

HIV's reverse transcriptase is extremely error-prone. (our replication enzymes make errors too, but we have effective proof-reading mechanisms).

[mortonman1]

O alright. i see kinda what you mean. Well thank you