The interaction of myotropic and macrophagotropic strains of Trypanosoma cruzi with myoblasts and fibers of skeletal muscle.

The process of interaction of bloodstream trypomastigotes from the myotropic CL and Colombiana strains and the macrophagotropic Y strain of Trypanosoma cruzi with mouse myoblasts and myotubes was analysed. After 24 h of parasite-host cell interaction, parasites from the CL and Colombiana strains appeared to be more infective to myoblasts than those from the Y strain. Parasites from the Colombiana strain were more infective for myotubes than those from the Y strain, while those from the CL strain showed very a low ability to infect the cells. For all strains the infectivity was low for short periods of interaction, increasing with time. Myoblasts infected with parasites from the Y strain fused with other infected and uninfected cells to form myotubes. However, the process of fusion was blocked when the myoblasts were infected with parasites from the CL and Colombiana strains. These data indicate a different behavior of muscle cells when in contact with myotropic or non-myotropic strains of T. cruzi.