CYST FORMATION BY TOXOPLASMA-GONDII IN-VIVO AND IN BRAIN-CELL CULTURE- A COMPARATIVE MORPHOLOGY AND IMMUNOCYTOCHEMISTRY STUDY

Formation of Toxoplasma gondii cysts was examined in cultured murine b rain cells and was compared with the development of cysts in mouse-bra in tissue. Cultures of mixed glial cells from neonatal mouse brain wer e infected with bradyzoites of the avirulent T. gondii strain DX. The development and maturation of Toxoplasma cysts was monitored for up to 63 days after inoculation. Transmission electron microscopy indicated that in-vitro-derived cysts were morphologically similar to tissue cy sts and were located intracellularly, even for up to 63 days postinfec tion. For immunohistological and immunocytochemical examination of bot h in-vivo- and in-vitro-infected material, monoclonal antibody (mAb) C C2 was used. MAb CC2 was shown to detect specifically the underlying g ranular material of the cyst wall without binding to the limiting memb rane of the parasitophorous vacuole. This reactivity of mAb CC2 allows the distinction of bradyzoite-containing cysts from parasitophorous v acuoles harboring tachyzoites both in vitro and in vivo.