Mouse Models of Uncomplicated and Fatal Malaria

Abstract

Mouse models have demonstrated utility in delineating the mechanisms underlying many aspects of malaria immunology and physiology. The most common mouse models of malaria employ the rodent-specific parasite species Plasmodium berghei, P. yoelii, and P. chabaudi, which elicit distinct pathologies and immune responses and are used to model different manifestations of human disease. In vitro culture methods are not well developed for rodent Plasmodium parasites, which thus require in vivo maintenance. Moreover, physiologically relevant immunological processes are best studied in vivo. Here, we detail the processes of infecting mice with Plasmodium, maintaining the parasite in vivo, and monitoring parasite levels and health parameters throughout infection.

Figure 1. Preparation of thin-film blood smears

A. Transfer a drop of blood onto a microscope slide. B. Side-view: Place the edge of a second slide at a 45° angle, allowing the blood to spread across the edge of the second slide. C. Top-view: Place the edge of a second slide at a 45° angle, allowing the blood to spread across the edge. D. A glass scoring tool and snapped slide fragments. Properly snapped slides should not have sharp edges. E. Place three smears on a single microscope slide for convenience when staining and counting large numbers of smears.

Figure 2. The major Plasmodium life cycle stages observed in blood

Example images of ring trophozoites (commonly referred to as “rings”), late stage trophozoites, and very late stage schizonts are shown. Note that the schizonts in these images have segmented into individual merozoites, which immediately precedes parasite egress. All images are P. berghei ANKA; P. chabaudi AS rings have a similar appearance to P. berghei ANKA rings.

Figure 3. Parasitemia and survival courses for commonly used Plasmodium strains in mice

A. The course of P. chabaudi AS parasitemia in female C57BL/6 mice. Data were pooled from two independent experiments (n=11). B. The course of P. yoelii 17XNL parasitemia in C57BL/6 mice. Data were from one experiment (n=5). C. The course of P. berghei ANKA parasitemia (n=14; pooled from two independent experiments) and survival (n=28; pooled from three independent experiments) in C57BL/6 mice. Shaded boxes represent our preferred window for passaging the infections. Parasitemias are presented as geometric means with SEM.

Figure 4. Cardiac Puncture

A. Insert the needle approximately 0.5 cm into the thoracic cavity. At this point, pull approximately 50 μl of volume to create a very light vacuum. B. Slowly advance the needle until puncturing the heart. Note the visible flash of blood entering the needle base. C. Slowly pull on the plunger, filling the syringe with blood.