THE MAJOR 85-KD SURFACE-ANTIGEN OF THE MAMMALIAN FORM OF TRYPANOSOMA-CRUZI IS ENCODED BY A LARGE HETEROGENEOUS FAMILY OF SIMULTANEOUSLY EXPRESSED GENES

Trypanosoma cruzi is an obligate intracellular protozoan parasite. The parasite mammalian stage surface antigens exhibit extensive antigenic diversity. We have characterized a family of T. cruzi genes that code for a polymorphic set of85-kD surface antigens, the SA85-1 antigens. The family contains >100 genes and pseudogenes, of which a minimum of nine are transcribed. The gene family is expressed in the mammalian stage only. A subset of the gene family is present in two Teomere-linked copies in the genome. Telomere linkage of other expressed SA85-1 genes has not been demonstrated. We have shown that at least three members of the SA85-1 gene family encode antigens at the surface of the mammalian stage of the parasite. Interestingly, these three antigens are expressed on all the trypanosomes examined. This suggests that T. cmzi simultaneously expresses a large repertoire of similar, but diverse antigens at its surface. Thus, T. cruzi exhibits extensive antigenic diversity in a system unique from that ofAfrican trypanosomes, perhaps reflecting its intracellular niche. © 1990, Rockefeller University Press., All rights reserved.