Immunological Dominance of <i>Trypanosoma cruzi</i> Tandem Repeat Proteins

<jats:title>ABSTRACT</jats:title> <jats:p> Proteins with tandem repeat (TR) domains have been found in various protozoan parasites, often acting as targets of B-cell responses. However, the extent of the repeats within <jats:italic>Trypanosoma cruzi</jats:italic> , the causative agent of Chagas’ disease, has not been examined well. Here, we present a systematic survey of the TR genes found in <jats:italic>T. cruzi</jats:italic> , in comparison with other organisms. Although the characteristics of TR genes varied from organism to organism, the presence of genes having large TR domains was unique to the trypanosomatids examined, including <jats:italic>T. cruzi</jats:italic> . Sequence analyses of <jats:italic>T. cruzi</jats:italic> TR genes revealed their divergency; they do not share such characteristics as sequence similarity or biased cellular location predicted by the presence of a signal sequence or transmembrane domain(s). In contrast, <jats:italic>T. cruzi</jats:italic> TR proteins seemed to possess significant antigenicity. A number of previously characterized <jats:italic>T. cruzi</jats:italic> antigens were detected by this computational screening, and several of those antigens contained a large TR domain. Further analyses of the <jats:italic>T. cruzi</jats:italic> genome demonstrated that previously uncharacterized TR proteins in this organism may also be immunodominant. Taken together, <jats:italic>T. cruzi</jats:italic> is rich in large TR domain-containing proteins with immunological significance; it is worthwhile further analyzing such characteristics of TR proteins as the copy number and consensus sequence of the repeats to determine whether they might contribute to the biological variability of <jats:italic>T. cruzi</jats:italic> strains with regard to induced immunological responses, host susceptibility, disease outcomes, and pathogenicity. </jats:p>