Immunity to malaria using the rodent malaria parasite Plasmodium chabaudi chabaudi AS as a model of the human malaria Plasmodium falciparum

The role of IFN in acquisition of immunity against erythrocyte forms of P.c. chabaudi AS was studied. Inbred NIH mice given the construct 7 days before malaria infection, showed a significant delay in the onset and in the level of the recrudescent parasitaemia in comparison with controls. No differences, however, were observed in the recrudescent parasitaemia between the groups. NIH mice infected with malaria 3 days after or on the same day as the administration of the IFN construct, showed a primary peak of infection similar to controls, but the resolution of this patent parasitaemia occurred 1 or 2 days earlier in the experimental mice when compared with controls. In the same experiment, mice given the construct 10 days before malaria infection had a similar course of infection as controls. Simultaneous inoculation with two S. typhimurium constructs: IFN and TNF, 8 days before malaria infection resulted in a course of parasitaemia similar to that observed in mice given the IFN construct alone. On the other hand, inoculation of 'susceptible' inbred A/J mice with S. typhimurium/IFN 3 or 8 days before malaria infection had no effect on the course of the parasitaemia when compared with controls. The immune mechanisms involved in the better control of the malaria infection of NIH mice given S. typhimurium/ IFN, seem to be independent of nitric oxide (NO) production, since increased levels of the molecule were demonstrable around the peak of the primary parasitaemia in control groups but not in experimental mice. In the latter basal levels of serum NO were observed from the period after the S. typhimurium/ IFN inoculation until up to three days after the peak of the parasitaemia