Cloned lines of Plasmodium berghei ANKA differ in their abilities to induce experimental cerebral malaria

Abstract

Infection with Plasmodium berghei ANKA is usually lethal. The parasite causes in some mouse strains a neurovascular syndrome, experimental cerebral malaria (ECM), involving immunopathological reactions. The effects on the development of ECM of the mouse genetic background have been clearly demonstrated, but nothing is known about the effects of the clonal diversity of the parasite. We showed that various cloned lines derived from a polyclonal line of P. berghei ANKA caused ECM but that the extent of ECM induction was dependent on the amount of inoculum. Subtle differences in ECM characteristics (survival time and hypothermia) were also observed. We also confirmed, using the 1.49L cloned line, that the mouse genetic background strongly affects ECM.

FIG. 1

Survival (A), body temperature (B), and parasitemia (C) after infection of 12 C57BL/6 mice with 10⁶ PE of the P. berghei ANKA polyclonal line. This experiment is experiment 4 reported in Table 1. + ECM, mice with neurological signs of ECM; − ECM, mice with no neurological signs of ECM. Mortality is indicated at the top of panel C as the number of mice that died on that day, and each curve represents the progression of a single mouse.

FIG. 2

Survival (A) and cumulative percentage of C57BL/6 mice displaying a body temperature below 35°C (B) after infection with 2 × 10⁶ PE of four P. berghei ANKA cloned lines. Symbols: ○, line 1.49L; □, line 1.97L; ▵, line 4; ▿, line 5.

FIG. 3

Parasitemia of C57BL/6 mice infected with four P. berghei ANKA cloned lines. Mortality is indicated at the top of each panel as the number of mice that died on that day. Each curve represents the progression of a single mouse.