Joao Miguel N. Batista <df20728 at fisis3.cc.fc.ul.pt> wrote:
: I'm sorry if this might not be the appropriate group to pose questions,
: but here goes anyway.
This is the perfect site...
: 1- It is known that the HIV virus infects helper T cells, and that its
: "entry" is done by attaching to the CD4 on the T cell surface. If T
: cells expressed class I MHCs, then cytotoxic T cells could recognize
: and destroy helper T cells infected with a strange virus. Now, my
: questions on this point are:
: a) Does the infected helper T cell produce virus peptides after
: its entry?
Yes... HIV however can be quiet and a T cell, though infected, may not
express any viral proteins... Also don't forget that Th cells are required
for CTL activation... In late stages of HIV infection, inhibition and
decrease in CD4 counts ultimately decreases activation of CTL's...
: b) Why the helper T cells do not express class I MHCs on their
: surface like so many other body cells? By the way, do cytotoxic
: T cells express them?
MHC class I's are expressed on ALL nucleated cells/. They are on T cells,
B cells and macrophages... MHC II's however are not expressed on quiescent
T cells but only on activated T cells. They are present on B-cells and
Macrophages..
: 2- I understand there are two classes of HIV virus identified, namely
: HIV-1 and HIV-2. What are the differences between them?
There is over 50% difference in the genetic sequence between the two.. The
majority of the differences reside in the envelope glycoproteins (
actually blodd banks have to use two different tests to ensure the absence
of both.. Ab's to one gp do not cross react with the other..
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C A N A D A
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Shahram Mori
Program in Molecular Biology
Department of Chemistry and Biochemistry Box 3C
New Mexico State University
Las Cruces NM
88003
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