FIG. 1. Infection of Hepal-6 cells by P. yoelii. P. yoelii sporozoites (parasite line 17XNL) were obtained from dissection of Anopheles stephensi salivary glands 14 days after the infective blood meal. Salivary glands were dissected out of infected mosquitoes in RPMI 1640 medium, transferred to an eppendorf tube, disrupted with a plastic homogenizer to free the parasites, and spun at 20g for 5 min to remove mosquito-derived debris. 105 P. yoelii sporozoites were added to monolayers of the Hepal-6 cell line grown on 12-mm glass coverslips (105 cells plated 24 h before in 24-well dishes) and dishes were spun for 5 min at 1800g. Cells were grown at 37C with 5% CO2 in DMEM medium supplemented with 10% fetal calf serum, 100 units/ml of penicillin, 0.1 mg/ml streptomycin, and 0.29 mg/ml glutamine. Coverslips were fixed for 10 min with cold methanol at 24 and 48 h after infection, before staining with anti-HSP70 monoclonal antibody (2E6)(Tsuji et al. 1994), followed by FITC-labeled antimouse secondary antibodies. EEFs are shown in white. Hepatocyte cell nuclei were stained with 1 μg/ml propidium iodide for 5 min and are shown in gray. Bar corresponds to 10 μm.

This showed a large number of infected cells, especially in Hepal-6 Hepal-6 cells by P. yoelii is highly reproducible, with infection levels typically varying from 200 to 400 EEFs/105 cells. Confirming previous cell line (Fig. 2). The infectivity levels of Hepal-6 by P. yoelii were even higher than the standard in vitro model of infection of HepG2 results (Calvo-Calle et al. 1994), HepG2 cells were not infected by