Immunological purification and partial characterization of variant-specific surface antigen messenger RNA of Trypanosoma brucei brucei.

Polyadenylated RNA isolated from total polyribosomes of two variable antigen types (VATs) of T. brucei brucei were shown to program the synthesis, in mRNA-dependant reticulocyte lysates, of a wide variety of polypeptides. After immunoprecipitation of these cell-free products with an homologous antiserum raised against purified variant-specific surface antigen (VSSA), a major electrophoretic band was apparent on fluorography. It was confirmed that this band corresponds to the variable antigen since only an excess of purified homologous antigen will provoke competition. The apparent molecular weight of the in vitro synthesized antigen is about 63,000 daltons. The VSSA mRNA has been found in membrane-bound polyribosomes and a 15 fold immunological purification of this mRNA has been obtained, using partially purified anti-VSSA IgG in conjunction with inactivated Staphylococcus aureus.