The variant surface glycoproteins of Trypanosoma equiperdum

The cross‐reacting antigenic determinant in the variant surface glycoproteins (VSGs) of Trypanosoma equiperdum was studied by testing the ability of VSG glycopeptides to bind heterologous anti‐VSG sera. VSG glycopeptide purification revealed the presence of 3 oligosaccharide sidechains on the mature VSG. These consist of two sidechains containing only mannose and glucosamine and a third containing galactose and mannose (in a 5 : 1 ratio) as well as phosphorous and ethanolamine. This phosphorylated fragment completely blocked the binding of VSG to heterologous anti‐VSG and therefore contained the cross‐reacting determinants.