ALTERATIONS OF TOXOPLASMA-GONDII INDUCED BY 2',3'-DIDEOXYINOSINE IN-VITRO

The time-course of action of the antiviral agent 2',3'-dideoxyinosine (ddI) against Toxoplasma gondii tachyzoites in vitro and its effects a t the ultrastructural level were investigated. The very short latency of effect and high efficacy of ddI were evidenced by the fact that the drugs' effects on parasite growth occurred 2 hr after addition to the culture medium, and that an IL90 value of 0.5 mu g/ml was reached aft er 72 hr. Although without apparent effect on uninfected cells, ddI cl early acted on the intracellular parasites, which tended to disappear. Remaining tachyzoites were almost exclusively extracellularly located and often exhibited a clustering of mitochondria-like bodies and subs equent deep alterations of their plasma membranes. These results confi rm previous findings and emphasize the potential usefulness of ddI in the management of cerebral toxoplasmosis, a major health problem in ac quired immune deficiency syndrome patients.