Chronic murine Chagas' disease: the impact of host and parasite genotypes.

Chagas' disease is a protozoan infection caused by the flagellate Trypanosoma cruzi. Herein we utilise experimental infections of different mouse and parasite strains to investigate the relative importance of the host and parasite genotype, respectively, in causing Chagas' disease in mice. CBA/J and BALB/c mice infected with the Tulahuen strain of T. cruzi develop a severe acute disease characterised by transient parasitaemia and a high rate of mortality. While the acute phases in these mice are indistinguishable, they display differential outcomes of the infection since CBA/J mice eventually develop polymyositis and mild myocarditis whereas BALB/c mice are resistant to chronic disease. In contrast, BALB/c mice infected with the CA-1 clone of T. cruzi exhibit a mild acute phase, develop no polymyositis but do develop severe myocarditis. Thus both the parasite and host genotype, but not the severity of the acute phase, are important in determining the eventual outcome of T. cruzi infection. We also present a murine model suitable for investigating which host factors may be necessary to induce a chronic inflammatory disease after T. cruzi infection.