Protection of squirrel monkeys against virulent Plasmodium falciparum infections by use of attenuated parasites

Abstract

We previously showed that the Uganda Palo Alto line of Plasmodium falciparum propagated in Saimiri monkeys and the line maintained in culture in human erythrocytes for many years in our laboratory are genetically unrelated (T. Fandeur, S. Bonnefoy, and 0. Mercereau-Puijalon, Mol. Biochem. Parasitol. 47:167, 1991). When injected into a splenectomized Saimiri monkey, the in vitro-derived Palo Alto population procured a long-lasting, low-grade parasitemia that was spontaneously resolved by the animal. This line was propagated by serial blood transfers in two other monkeys without enhancement of the virulence of the parasites. The genetic characteristics of parasite samples corresponding to the different passages of the line in monkeys were stable for the several markers examined (pPF11.1, MSA1, and MSA2), although microheterogeneity was detected in telomeric and subtelomeric regions of chromosomes. Interestingly, in vitro-derived Palo Alto

Transmission intensity and Plasmodium falciparum diversity on the northwestern border of Thailand.

“…Superinfection data from induced P. falciparum infections in humans and Saimiri monkeys have shown that immunity is predominantly strain-specific and weakly cross-strain specific. 36,37 Induced infection experiments in rodent models also support this conclusion. [38][39][40] Such an explanation is highly speculative and further data on both the duration of infection and gametocyte rates across transmission intensities are required.…”

The RESA-2 gene of Plasmodium falciparum is transcribed in several independent isolates

“…1, SAg, MSA1, MSA2, RESA, PfPArep20, and telomere markers (7). The genetic characteristics of these parasites as well as their infectivity for splenectomized Saimir monkeys have been fully detailed elsewhere (7)(8)(9).…”