CYTOTOXIC T-LYMPHOCYTE-MEDIATED LYSIS OF TOXOPLASMA GONDII-INFECTED TARGET-CELLS DOES NOT LEAD TO DEATH OF INTRACELLULAR PARASITES

CD8(+) T cells play a crucial role in the control of infection with in tracellular microbes. The mechanisms underlying the CD8(+) T-cell-medi ated clearance of the intracellular pathogen Toxoplasma gondii are, ho wever, not completely understood. The effect of CD8(+) cytotoxic T-lym phocyte (CTL)-mediated lysis of host cells on the viability of intrace llular T. gondii was investigated. Quantitative competitive PCR of the gene encoding T. gondii major surface antigen (SAG-1) was combined wi th treatment of the parasites with DNase, which removed the DNA templa te of nonviable parasites. The induction by CD8(+) CTLs of apoptosis i n cells infected with T. gondii did not result in the reduction of liv e parasites, indicating that intracellular T. gondii remains alive aft er lysis of host cells by CTLs.