 The profile of the major oligosaccharides linked to CA125 and the major surface glycoprotein of HIV-1 (gp120) almost perfectly overlap.More persistent pathogens linked to the eu-FEDS model may be identified as mass spectrometry methods for sequencing oligosaccharides become more sensitive.Several other models have been developed that seek to address this hypothetical system for immune tolerance, including the depletion of tryptophan via the enzyme indoleamine dioxygenase (IDO) and the expression of the nonclassical MHC class I molecule designated HLA-G.