Does HIV antibody kill HIV? - (Sep/08/2006 )
Hi all,
A person develops anti-HIV antibody when he or she is infected by the virus. It means that the virus does trigger T helper2 cells to stimulate B cell to produce antibodies. But why the virus is not killed by the antibody?
Is it because of mutation that change the surface antigen of the bug or not enough antibodies produced? 
??
Thanks!
You have a very high amount of virus in the blood, so some virusses will escape and mutate so that they escape the antibody's in the long run.
Severall antibody's aren't even targeted towards the surface antigen, but towards core antigens (that are released from infected cells) like the most known (I think) p24 antigen. And even a lot of antibody's targeted towards the surface glycoproteins (the glycosylated parts are protected from any antibody from targetting them) aren't neutralising so even when the antibody's are around they offer no protection from another cell becoming infected.
part of the problm lies in that HIV replicates in T-cells, therefore if you have an immune response, then you get more T-cells produced, which allows more replication of the HIV etc.
A highlightened point is
the potential for mutations in HIV is enormous over a billion virus particles are made every day by an infected patient, even in the early stages of infection, and on average each contains one mutation. This gives the virus the power to escape from both the killer cells and antibodies. Some patients are more lucky than others, however. The virus cannot mutate certain parts of its genes without damaging its ability to survive and replicate. Some people infected with HIV may be able to generate a more effective immune response to the virus if their particular HLA molecules happen to pick peptides from these 'conserved' regions.
unfortunely these conserved surface protein... such as the docking receptor that allow the HIV virus to lock on and gain entry into its host celll is surrounded and protected by proteins that do change rapidly.
To be a bit more precise about this (I'm working on HIV entry myself).
the envelop of HIV consists of 2 heavily glycosilated proteins, the surface gp120 and the transmembrane gp41. Due to the heavy glycosylation, they are for a large part protected from antibody response.
Secondly, several functionally very important epitopes are only "surfaced" during a small timeframe between adhesion of the virion and release of the capsid into the host cell, so it's hard to establish antibody response to these functionally important epitopes. Apart from this, the envelop is the most variable region of the virus, which means that the virus has a lot of potential to generate escape mutations (as stated, about 1 mutation is introduced into each virus) and still generate viable virusses. given the large number of virusses generated each day (as correctly stated above) enough viable virusses will be generated that can escape the potential antibody response.
Certain mutations can lead to reduced replication of the virus but they can be compensated by other mutations in the longer run (once again, rather easily generated by the error prone replication).
Cheers.
ciao,
Mike