Different patterns of disease in two inbred mouse strains infected with a clone of Leishmania mexicana amazonensis.

We have infected BALB/c and C57BL/6 mice with a cloned Leishmania mexicana amazonensis population, obtained from the "Maria" strain. Progression of infection and histopathological examination confirmed the extreme susceptibility of BALB/c mice and the resistant pattern of the C57 BL/6. Anti-Leishmania antibody titers were higher in BALB/c than in C57BL/6 mice through the period of infection. Tests of delayed type hypersensitivity reaction with Leishmania antigens were positive in both strains in the beginning of the infection, but were negative later on in BALB/c mice. Our results are similar to those obtained with mixed parasite populations, and rule out the possibility of selection among different parasite subpopulations as responsible for the divergent course of the disease exhibited by these two strains of mice.