why can..???

Question

Why can HIV attach itself to a helper T cell (T4 lymphocyte), but cannot attach itself to a skin cell?

Answer 1

HIV primarily infects vital cells in the human immune system such as helper T cells (specifically CD4+ T cells), macrophages and dendritic cells.
The interactions of the trimeric envelope complex (gp160 spike, discussed above) and both CD4 and a chemokine receptor (generally either CCR5 or CXCR4 but others are known to interact) on the cell surface.[54][55] The gp160 spike contains binding domains for both CD4 and chemokine receptors.[54][55] The first step in fusion involves the high-affinity attachment of the CD4 binding domains of gp120 to CD4. Once gp120 is bound with the CD4 protein, the envelope complex undergoes a structural change, exposing the chemokine binding domains of gp120 and allowing them to interact with the target chemokine receptor.[54][55] This allows for a more stable two-pronged attachment, which allows the N-terminal fusion peptide gp41 to penetrate the cell membrane.[54][55] Repeat sequences in gp41, HR1 and HR2 then interact, causing the collapse of the extracellular portion of gp41 into a hairpin. This loop structure brings the virus and cell membranes close together, allowing fusion of the membranes and subsequent entry of the viral capsid.

Answer 2

Viruses have a simple structure of genetic material and a protein coat. The protein coat also contains spikes called glycoproteins. Glycoproteins identify the virus and help it attach to a cell membrane.

The way viruses attach to a cell membrane makes the viruses really specific. The glycoproteins attach to specific receptors on the cell membrane. The receptors are actually for things the cell needs, like food, etc, but viruses adapted glycoproteins that fit into the receptors so they can be sneaky. The glycoprotein only fits in one receptor, and different kinds of cells have different receptors.

In the case of HIV, it developed to fit into the receptors of a helper T cell, not a skin cell. Therefore, it could not enter the skin cell.

Answer 3

Because all cells have specific receptors on it and HIV is dialed in to coerce the T4 cells into thinking it's good for the cell. Other cells don't have the receptor that HIV hijacks in this manner.

Answer 4

I am not sure