THE BIOCHEMISTRY OF THE SURFACE ANTIGENS OF THE AFRICAN TRYPANOSOMES

The African trypanosomes owe their ability to survive within the bloodstream of their mammalian hosts to their ability to undergo antigenic variation. The continuous development of antigenically distinct variants in the course of infection ensures that some trypanosomes always survive the development of an immune response to propagate the infection. Antigenic variation is a consequence of changes in the composition of the surface coat which covers the entire surface of the trypanosome. The surface coat on any one trypanosome is composed of a matrix of about 107 identical glycoprotein molecules, which show remarkable sequence diversity when different variants are compared. The biochemistry of these unusual glycoproteins is reviewed.