Protocol for Assaying CTL Activity Against Toxoplasma gondii
Tachyzoites of the ts-4 strain of T. gondii are maintained by in vitro passage in human foreskin fibroblasts at 33°C. T. gondii soluble antigens (STAg) are prepared from parasites obtained by peritoneal lavage, 3 days after infection of Swiss Webster mice with 5–10 × 106 RH strain tachyzoites. Tachyzoites are concentrated by centrifugation (1500 × g, 10 min) and repeatedly sonicated until no intact parasites remain. After centrifugation at 10,000 × g for 30 min, the supernatant is collected, dialyzed against PBS, and stored at −80°C.