Ultrastructure of in vitro cultured exoerythrocytic stage of Plasmodium berghei in a hepatoma cell line.

Because of difficulties in cultivation of the exoerythrocytic (EE) stages of mammalian malaria parasites, investigation of the development of the EE stages has been hindered as compared to that of the other stages. Recently, human hepatoma cells (HepG2-A16) have been shown to be useful for the complete developmental cycle of the EE stage of Plasmodium berghei. In order to define the morphological events during this process, we evaluated the EE stages developing from sporozoites in these human hepatoma cells using electron microscopy and compared their structure to those grown in vivo. This study demonstrates that sporozoites of P. berghei can transform into EE stages within the hepatoma cells in a manner morphologically identical to that seen in vivo, and suggests that this cell line is a useful model for the study of the EE stages of mammalian malaria parasites.