The immune system cells are called the CD4 or T cells.

Nah. The CD4 cells are just subclasses of the T-lymphocytes which are immune cells. We have the CD8 cells too. The neutrophils, basophils and basically all cells of the recticuloendothelial system are also cells of the immune system.

Mutation in the CCR- Delta 35 receptors only offers resistance to the HIV-1 virus. This does not apply to other strains of the HIV virus.

This is an interesting read however. Good to see this simply explained.