The 70-kDa heat-shock protein is a major antigenic determinant in human Trypanosoma cruzi/Leishmania braziliensis braziliensis mixed infection.

Five sera from Bolivian individuals chronically infected by Trypanosoma cruzi, and suffering an active Leishmania braziliensis braziliensis metastatic mucocutaneous lesion were characterized. They reacted with the T. cruzi recombinant antigens that are currently used as Chagas diagnostic reagents, and with several L. b. braziliensis proteins as assessed by Western blot. These sera showed an intense reaction with a T. cruzi and an L. b. braziliensis polypeptide of about 70 kDa. Expression cloning techniques demonstrated that the target of this immunologic reaction was a cross-reactive antigen, the 70-kDa heat-shock protein (HSP 70). High levels of anti-HSP 70 reactivity and positive reactions with all or some of the T. cruzi recombinant antigens JL7, JL8, and JL5, defined a serologic pattern that was characteristic of the T. cruzi/L. b. braziliensis mixed infection.