ABSTRACT
Objective: To understand the morphologic foundation for differences in drug-resistance, virulence and immunity between chloroquine-sensitive (N) and chloroquine-resistant (RC) strains of Plasmodium berghei. Methods: The RC strain and the N strain were compared concerning the formation and morphologic features of digestive vacuoles and haemozoin with transmission electron microscope. Results: There was a single large digestive vacuole and multiple micro-single-mem-braned vacuole-like structures in the trophozoites of the N strain, and haemozoins centralized and fused during their schizo-gony were situated under the plasma membrane. Whereas there were few digestive vacuoles in the trophozoites of the RC strain, but with multiple micro-single-membraned vacuole-like structures instead. The RC strain formed obviously less hemo-zoins than that of the N strain and the hemozoins were not centralized and fused during the schizogony. Conclusion: The RC strain forms multiple single-membraned food vacuole-like structures in the trophozoites, and has different mechanism for detoxifying free heme with N strain and the features may be the foundation for the difference in drug-resistance, virulence, immunity between RC strain and N strain of Plasmodium berghei.