A monoclonal antibody to Trypanosoma cruzi trypomastigotes recognizes a myosin tail epitope

A monoclonal antibody, 1E7. raised against tissue culture-derived trypomast igotes of Trypanosoma cruzi reacted with proteins located at the perinuclea r region of the parasite as detected by immunofluorescence and immunogold e lectron microscopy. The antibody also recognized antigens in all trypanosom atids tested, including T. cruzi epimastigotes, as well as in many mammalia n cells. Five principal antigens of 140-270 kDa soluble in 1 M NaCl were re cognized by the monoclonal antibody, suggesting that the epitope may belong to more than one polypeptide since the same bands appeared even when the s amples were treated with high concentrations of denaturing agents. The anti body reacted in Western blots with muscle myosin. Bacterial clones expressi ng fast skeletal muscle myosin head or tail cDNAs upon IPTG induction were used to demonstrate that 1E7 monoclonal antibody recognizes an epitope pres ent in the tail region of the myosin heavy chain. This result adds to the o ngoing discussion related to the possible existence of an auto-immune compo nent in the immunopathogenesis of Chagas' disease due to cross-reactive epi topes shared by the parasite and cardiac myosin.