HLA-E and Infertility: When we looked at NKG2D and NKG2A ligands expression by endometrial cells from infertile HHV-6A positive and negative women and fertile women, we observed a slight reduction of HLA-E and a significant decrease in NKG2D ligands expression in HHV-6A positive infertile women (Figure 5D) (p < 0.001, Student’s t-test).