A comparative ultrastructural study of the low virulent strain PV-C1/81 and RH strain cultured in A9, Vero, SIRC cell lines.

A human Toxoplasma strain, isolated in mice from bioptic lymphoglandular tissue, has been cultured in vitro in continuous cell lines. Its presence in some parastized cells, with parasitophorous vacuoles surrounded by a cyst-like wall and filled with a cystozoite-like clone, was observed by electron microscopy. These characteristic and constant features were confined in different cell line cultures and are suggested as possible markers of low virulent strains.