Electron microscopic analysis confirms that p52/p36-deficient parasites cannot form a parasitophorous vacuole. (A) wt sporozoite (longitudinal view) within a HepG2-CD81 cell 1 h after infection. The parasite is surrounded by a PVM. (B) p52/p36-deficient sporozoite (transversal view) within a HepG2-CD81 cell 1 h after infection. The parasite lacks a PVM and appears to be in direct contact with the host cell cytoplasm. (C) A p52/p36-deficient sporozoite (transversal view) was also detected within the host cell nucleus, surrounded by nucleoplasm. All scale bars are 0.5 μm. The inset boxes show higher magnifications of the boxed areas within the overview images. ER, endoplasmic reticulum; IMC, inner membrane complex; M, microneme; NE, nuclear envelope; PPM, parasite plasma membrane; Spz, sporozoite; Rh, rhoptry.