Early clinical observations from HIV infected individuals showed lower L-selectin expression on T cells and neutrophils compared to healthy controls or individuals on ART therapy, suggesting the viral infection caused protracted immune activation and dysregulated lymphocyte homing (Moore et al., 1998; Gainet et al., 1999; Meddows-Taylor et al., 2001; Schneider-Hohendorf et al., 2014). This evidence concerns the gene SELL and viral infectious disease.