CCR2 and HIV infectious disease: Therefore, chemokine receptors may also serve as an entry point for HIV infection into CNS.[15] CXCR4 receptors are expressed on neurons of brain of HAD patients.[16] Hippocampal neurons in HAD have been reported to be positive for CCR2, CCR3, and CCR4.[17] Microglia and neuron were also found positive for CCR2, CCR3, and CXCR4 in HAD.