Chronobiology ofPlasmodium chabaudi chabaudi :analysis of hourly recorded total and differential parasitaemia during a schizogonic cycle

Abstract

Summary :Detailed total and differential parasitaemia curves of asexual Plasmodium chabaudi chabaudi erythrocytic stages were recorded and analysed. Female, inbred, CBA/Ca mice were infected with the virulent IP-PC 1 strain after in vitro synchronization of the parasites. Thin blood smears were made on an hourly basis, and the total and differential parasitaemia of ring forms, trophozoites and schizonts were counted after Giemsa staining. These curves reveal information that remains hidden when less detailed curves are examined: the duration and periodicity of the schizogonic cycle, the existence of a plateau, indications of a schizont withdrawal from the peripheral blood, the timing of the rise of the parasitaemia at each schizogony, and the invasion rate of the merozoites. In the perspective of developing a rational and efficient strategy for chronotherapy of malaria, such information should be taken into account.KEY WORDS : malaria, Plasmodium chabaudi chabaudi, chronobiology, parasitaemia curves, schizogonic cycle. Résumé : CHRONOBIOLOGIE DE PLASMODIUM CHABAUDI CHABAUDI : ANALYSE DES COURBES HORAIRES DES PARASITÉMIES TOTALES ET DIFFERENTIELLES PENDANT UN CYCLE SCHIZOGONIQUE Des courbes détaillées de parasitémie totale et différentielle des stades érythrocytaires asexués de

Quantitative dissection of clone-specific growth rates in cultured malaria parasites

“…4B). Invasion rates are equally sensitive to starting parasitemia in both clones, an observation that is consistent with reports for Plasmodium chabaudi chabaudi (Chimanuka et al, 1997) in which lower starting parasitemia results in greater invasion efficiency.…”

A comparison of the stage-specific efficacy of chloroquine, artemether and dioncophylline B against the rodent malaria parasite Plasmodium chabaudi chabaudi in vivo

“…Indeed, between 17.00 hours and 19.00 hours, the presence of ring forms and few schizonts was more expected (Chimanuka et al 1997(Chimanuka et al , 1999 than the observed abnormally pigmented IRBCs. Also, we noticed that the change in malaria parasite morphology was clear from 17.00 hours, and was completed 2 h later (Fig.…”

“…Total and dierential parasitaemias were determined. The developmental stages of P. chabaudi were identi®ed and found conform with previously described de®nitions (Landau 1965;Cambie et al 1991;Chimanuka et al 1997Chimanuka et al , 1999. All surviving mice were kept for several weeks to check for long-term toxic eects.…”

Differential sensitivity of erythrocytic stages of the rodent malaria parasite Plasmodium chabaudi chabaudi to dioncophylline B, a highly active naphthylisoquinoline alkaloid

“…If gametocytes were observed, this fact was recorded, but no countings were made and the strain was not passed through a vector. All developmental stages were identi®ed according to earlier described criteria (Landau 1965;Landau et al 1978) and in some cases reinvasion rates were calculated (Chimanuka et al 1997). After the treatment, total parasitaemia was recorded once a day until the slides were found completely negative.…”

“…Its infections display a high degree of synchronicity with a period of 24 hours, and depend on the circadian rhythm of the host Landau et al 1990Landau et al , 1991. Therefore, it is a suitable model for the exploration of the chronobiology of malaria parasites (Chimanuka et al 1997) and for the investigation of chronotherapeutic antimalarial tools (Landau et al 1992). In this sense, the aim of this work was to examine the dierential sensitivity of P. chabaudi chabaudi asexual erythrocytic stages to dioncophylline B.…”