Cytokine and lymphocyte profiles in miniature swine after oral infection with Toxoplasma gondii oocysts

Pigs are considered an important source of Toxoplasma gondii infection for humans. A major strategy for immune prophylaxis of toxoplasmosis in swine i s the understanding of the immune response against T. gondii infection, The phenotype of peripheral blood mononuclear cells (PBMC) and the kinetics of interferon-gamma (IFN-gamma), interleukin-12 (IL-12) and interleukin-10 (I L-10) transcriptional changes were characterised in miniature swine followi ng infection. A total of 66, 4-9-month-old miniature swine were used for th ree experiments performed over a period of 2 years. All pigs were fed 1000 oocysts of the VEG strain of T. gondii and blood samples were obtained on t he day of inoculation and at days 3, 6, 10, 17, 25, 32 and 40 after infecti on. An increase in expression of activation markers CD25 and SLA-DQ was det ected in the first week of infection. A significant increase in the percent age of CD8+ cells was observed in the second week of infection. Relative co mpetitive RT-PCR analysis indicated an increase in IFN-gamma mRNA as well a s a reduction in IL-10 mRNA during the second week post infection. Increase in IL-12 transcription was not observed until the fourth week of infection . The ability of the pigs to respond to T. gondii infection by simultaneous ly inducing pro-inflammatory cytokines early and anti-inflammatory cytokine s later is a likely indication of the requirement to strike a balance betwe en controlling parasite growth and avoiding cytokine toxicity. (C) 2001 Aus tralian Society for Parasitology Inc. Published by Elsevier Science Ltd. Al l rights reserved.