The receptor for CXCL13 is CXCR5 (BLR1) [8], and it has been shown that levels of CXCR5 are significantly decreased on the surface of circulating B cells during HIV infection, and that these cells, in contrast to B cells from healthy individuals, express CXCL13 [12,13]. This evidence concerns the gene CXCR5 and HIV infectious disease.