Killing of intracellular parasites is associated with IFNβ production.

<p>(A) Microarray analysis of HFFs shows differentially expressed host genes belonging to the type I interferon pathway (rows) induced during infection with different <i>T. gondii</i> strains (columns). (B–C) HFFs monolayers were infected with either PRU or COUGAR parasites for two hours, and subsequently washed to remove extracellular parasites. At the indicated time points cells were fixed, permeabilized, and stained with anti-SAG1 and anti-GRA7 to visualize parasites and vacuoles respectively. Number of parasites per cell (B) and vacuoles per field (C) was determined by counting at least 60 infected cells and 5 microscope fields per condition. Error bars represent standard error. Data is representative of three independent experiments. * = <i>p</i><0.05. (D) HFFs monolayers where either pre-treated with IFNγ 100 u/ml for 24 hours or left untreated, and subsequently infected with <i>T. gondii</i> (PRU strain). After 20 hours of infection total RNA was isolated and expresion levels of <i>Ifnb1</i> was determined by qPCR. Data is representative of experiments done two times. (E) Immortalized murine macrophages were stimulated overnight with 2.5 µg/ml of <i>T. gondii</i> genomic DNA or Poly(dA∶dT) either naked or conjugated with transfection reagents that delivers nucleic acids to the cytoplasm (X-tremeGENE9) or endosomal compartments (DOTAP). Subsequently total RNA was isolated and expression levels of <i>Ifnb1</i> was determined by qPCR. Data is representative of two independent experiments.