CHARACTERIZATION OF A CDNA CLONE ENCODING THE CARBOXY-TERMINAL DOMAINOF A 90-KILODALTON SURFACE-ANTIGEN OF TRYPANOSOMA-CRUZI METACYCLIC TRYPOMASTIGOTES

We have cloned and sequenced a cDNA for a metacyclic trypomastigote-sp ecific glycoprotein, with a molecular mass of 90 kDa, termed MTS-gp90. By immunoblotting, antibodies to the MTS-gp90 recombinant protein rea cted exclusively with a 90-kDa antigen of metacyclic trypomastigotes. The insert of the MTS-gp90 cDNA clone strongly hybridized with a singl e 3.0-kb mRNA of metacyclic forms, whereas the hybridization signal wi th epimastigote mRNA was weak and those with RNAs from other developme ntal stages were negative, indicating that transcription of the MTS-gp 90 gene is developmentally regulated. A series of experiments showed t hat the MTS-gp90 gene is present in multiple copies in the Trypanosoma cruzi genome, arranged in a nontandem manner, and that there are at l east 40 copies of the gene per haploid genome. Sequence analysis of re combinant MTS-gp90 revealed 40 to 60% identity at the amino acid level with members of a family of mammalian stage-specific, 85-kDa surface antigens of T. cruzi. However, there are considerable differences in t he amino acid compositions outside the homology region.