HLA-G and HLA-C at the feto-maternal interface: lessons learned from pathogenic viruses

Immunoevasive viruses which effect antigen presentation by class I major histocompatibility complex (MHC) molecules have helped to broaden our understanding of the intracellular transport and processing of HLA-G and HLA-C in the placenta. Cellular infection with herpes simplex virus (HSV) and human cytomegalovirus (HCMV) are each associated with the downregulation of surface expression of HLA-A and -B, albeit by remarkably distinct mechanisms. Investigations on the effects of HSV and HCMV infection on HLA-G and HLA-C in the trophoblast have revealed both hypothesized similarities and surprising differences between trophoblast and classical class I products.