EXPRESSION OF 2 VARIANT SURFACE GLYCOPROTEINS ON INDIVIDUAL AFRICAN TRYPANOSOMES DURING ANTIGEN SWITCHING

Individual Trypanosoma brucei rhodesiense organisms were observed in the process of switching variant surface glycoproteins (VSG). During this switch, trypanosomes simultaneously expressed both pre- and postswitch VSG uniformly over their surface as detected with monoclonal antibodies. Analysis of this switching event showed that trypanosomes expressing any one of 3 distinct preswitch VSG could switch to expression of from 1-3 different postswitch VSG. Up to 2.7% of the trypanosome population was in the process of switching at one time.