A cryopreserved isolate of the virulent rodent malaria parasite
strain Plasmodium chabaudi chabaudi (IP-PC 1), originally from
the Pasteur Institute (Paris, France) was provided by the Depart-
ment of Cellular Immunology of the Vrije Universiteit Brussel (Bel-
gium). P. chabaudi chabaudi is a specific mouse malaria and does
not infect man. Immediately after thawing, the isolate was injected
intravenously in a mouse that later served as a donor to other mice.
After three mouse to mouse transfers of parasites, the last infected
mouse was bled by heart puncture using a heparinized 1 ml syr-
inge. The blood (1 ml) was suspended in 10 ml AlseverÒ medium
(glucose 1.86%, trisodium citrate 0.8% and sodium chloride 0.3%;
pH 7.2) and centrifuged at 400g for 10 min at room temperature.
The pellet was resuspended in AlseverÒ medium and the equiva-
lent of 106 infected erythrocytes was injected intravenously into
each mouse in the four groups. The parasitaemia was checked daily
from day 2 following the infection. A thin blood smear was made,
Giemsa stained and observed under a light microscope. The para-
sitaemia was estimated by counting more than 100 infected eryth-
rocytes against normal erythrocytes as previously described
(Chimanuka et al., 1999) with slight modifications.