Cloning and partial characterization of a 28 kDa antigenic protein of Trypanosoma cruzi.

Eleven antigenic clones were isolated from a Trypanosoma cruzi cDNA expression library using a pool of Chagasic sera from Venezuelan patients. These clones were tested with 26 Chagasic sera and 11 sera from patients with other diseases. One clone (Clone 2) reacted with the majority of the Chagasic sera and did not react with the non-Chagasic sera. Restriction enzyme digestion of Clone 2 DNA showed that it contained an insert of 5.2 kb. In a Southern blot of a pulse field gel electrophoresis, Clone 2 hybridized to three T. cruzi chromosomal fragments. By Northern blot analyses, it was observed that the clone hybridizes to a major T. cruzi RNA band of 0.97 kb and to two minor bands of 4.8 and 6.3 kb. The expression of these three RNAs was higher in trypomastigotes than in epimastigotes or spheromastigotes. Specific antibodies isolated against the beta-galactosidase-Clone 2 fusion protein expressed in E. coli reacted with a 28 kilodalton protein in T. cruzi.