Upregulation of both virus-infected cell surface membrane-bound HLA-G and peripheral soluble HLA-G expression has been observed in various viral infectious diseases, such as human immunodeficiency virus type 1 (HIV-1), herpes simplex virus-1, rhabdovirus, human cytomegalovirus, hepatitis B and C virus, and influenza A virus (63). Here, HLA-G is linked to viral infectious disease.