CD4 and infection: In the alterations at the GALT level, the virus’s tropism for cells expressing CD4 and co-receptors plays a key role, these may include the chemokine receptor CCR5 in early infections, or the CXC motif chemokine receptor CXCR4 in chronic infections, which are expressed on dendritic cells, memory T lymphocytes, mucosal-associated T lymphocytes, and cells of the monocyte–macrophage lineage [6].