Muscle sarcoplasmic reticulum antigen shared by a Trypanosoma cruzi clone.

The results reported here show that a clone of a South American Trypanosoma cruzi human isolate has an epitope antigenically related to sarcoplasmic reticulum adenosine triphosphatase preparations (SRA), an enzyme implicated in the contraction-relaxation cycle of striated muscle. The antigenic determinant of T. cruzi, which is cross-reactive with SRA, is located in the interior of the parasite. No surface cross-reaction was detected with intact, freely swimming flagellates. Indeed, the degree of cross-reactivity was increased when T. cruzi microsomes were trypsinized, probably resulting in further exposure of the normally internal cross-reactive epitope.