Relationship between the host cell endoplasmic reticulum and the parasitophorous vacuole containing Toxoplasma gondii.

Tachyzoites of Toxoplasma gondii multiplies within the parasitophorous vacuole (PV) of the host cell. Simultaneously with parasite division growth of the vacuole takes place. Using immunofluorescence microscopy and antibodies recognizing calreticulin, a nonmuscle functional analogue of calsequestrin, and a 76 kDa glycoprotein localized in the endoplasmic reticulum (ER), we showed the incorporation of ER elements of the host cell into parasitophorous vacuole containing-T. gondii. In addition enzyme cytochemistry showed that glucose-6-phosphatase, an enzyme marker of ER, is also localized within the PV. These observations suggest that growth of T. gondii -- containing PV is at least in part due to incorporation of elements of the host cell ER into the vacuole.