Studies of Trypanosoma cruzi clones in inbred mice. II. Course of infection of C57BL/6 mice with single-cell-isolated stocks.

A study of the course of parasitemia and mortality of C57BL/6 mice infected with the Trypanosoma cruzi Sylvio-X10 strain and two single-cell-isolate clones of the strain confirms our previous report on the existence of intra-strain subpopulations differing in their pathogenicity for inbred mice. In contrast to the generally accepted pattern of mouse strain susceptibility, C57BL/6 mice are more susceptible than C3H/HeN mice when infected with the Sylvio-X10 isolates. In addition, sex-related differences in susceptibility occurred depending upon the strain of the mouse and parasite isolate used. These data infer an interplay of host and parasite genetic factors influencing the outcome of a mouse infection with T. cruzi.