Stabilization and preservation of the antigenic specificity of Trypanosoma (Trypanozoon) brucei variant specific surface antigens by mild fixation techniques.

Living bloodstream trypansomes fixed by suspension in a 1% formalin solution maintain both their morphology and the immunological specificity of their variant specific surface glycoprotein, so allowing precise identification of the variant types present in a trypanosome population by direct or indirect immunofluorescence combined with phase microscopy. The technique is simple, adaptable to the study of low parasitaemias and should facilitate analysis of the phenomenon of antigenic variation both in the field and the laboratory.