Structure and expression of two Trypanosoma cruzi genes encoding antigenic proteins bearing repetitive epitopes

Trypanosoma cruzi genes were cloned in lambda gt11 and screened with an anti-trypomastigote antiserum. Two out of twelve clones were selected in view of their reactivity with human chagasic sera. One clone encodes a flagellar antigen (FRA) of more than 300 kDa, whereas the other corresponds to a roughly 225-kDa cytoplasmic antigen (CRA). The flagellar antigen is present in both epimastigotes and trypomastigotes, but the cytoplasmic antigen is not found in trypomastigotes. The CRA clone is entirely composed of at least 23 copies of a 42-bp repeat and the FRA gene contains at least 14 copies of a 204-bp motif. The FRA gene hybridizes to a RNA of about 10 kb, while the CRA gene detects a transcript of 5.2 kb.