No cell traversal

No cell traversal

Normal numbers of midgut- and salivary gland sporozoites are formed. Sporozoites showed wild type gliding motility. Sporozoites had lost cell passage ability (membrane-damaging capacity) as shown in the cell-wounding assay. Compared to wild type sporozoites, the mutant sporozoites were rapidly immobilized in the dermis. Mutant sporozoites were shown to be arrested by and invade dermal fibroblasts.

Normal numbers of midgut- and salivary gland sporozoites are formed. Sporozoites showed normal gliding mitility. Sporozoites have a strongly reduced infectivity (15-28 fold lower) to rats after intravenous injection of sprozoites and strongly reduced numbers of exoerythrocytic forms (EEFs) in frozen sections of rat livers (30-fold decrease) were counted 24 h after sporozoite inoculations.

No difference was noticed between wild type and mutant parasites in number, size, and fluorescence intensity of EEF at 4, 12, 24, or 48 hr in rat or mouse primary hepatocytes. Sporozoites show in vitro a 'rapid invader' phenotype, as a result of the lack of cell traversal. Mutant sporozoites show an adhesion/attachment phenotype (to CRL-2017 cells in vitro) which is comparable to wild type sporozoites.

Sporozoites have a strongly reduced infectivity (15-28 fold lower) to rats after intravenous injection of sprozoites and strongly reduced numbers of exoerythrocytic forms (EEFs) in frozen sections of rat livers (30-fold decrease) were counted 24 h after sporozoite inoculations. Sporozoites formed normal numbers of EEFs in hepatoma cells (HepG2), indicating that they retain normal infection ability. Sporozoites had completely lost cell passage ability as shown in the cell-wounding assay. Cell-passage activity was estimated by the number of cells wounded by sporozoite passage, which were identified by cytosolic labelling with FITC-conjugated dextran.In Kupffer cell-depleted rats, the sporozoites had restored liver infectivity. Parasitaemia after inoculation of mutant sporozoites was remarkably increased in Kupffer-depleted rats, becoming similar to that after inoculation of wild-type sporozoites In addition, the numbers of EEFs formed in the liver were also similar between spect-disruptants and the wild-type.