Two of the 18 human family members, secretory leukocyte protease inhibitor (SLPI) and Elafin display anti-HIV activity, correlating with reduced virus transmission [25-28]; however, a third member, whey acidic protein four-disulfide core domain 1 (WFDC1)/ps20, expressed in several mucosal tissues, enhances HIV infection [29]. This evidence concerns the gene SLPI and HIV infectious disease.