KINETICS OF INTERFERON-GAMMA PRODUCTION IN-VIVO DURING INFECTION WITHTHE S48 VACCINE STRAIN OF TOXOPLASMA-GONDII

The kinetics of interferon gamma (IFN gamma) production in vivo was ex amined in sheep during a primary and secondary infection with the shee p vaccine strain (S48) of Toxoplasna gondii. Efferent lymph plasma fro m a node draining the site of inoculation was tested for anti-viral ac tivity which could be neutralized with monoclonal antibodies against I FN gamma. Within 2 to 5 days of primary infection IFN gamma was detect ed in each of five sheep and persisted for 6 to 9 days. Accelerated pr oduction of IFN gamma occurred after secondary infection, the cytokine being detected in the first 24 h, and persisting in lymph for a furth er 4-5 days. From day 6 onwards after primary infection, efferent lymp h cells produced IFN gamma when stimulated in vitro with a crude T. go ndii antigen. These results show that IFN gamma is induced in sheep af ter infection with the S48 strain of T. gondii. (C) 1995 Academic Pres s Limited