Strain-specific activation of the type I interferon signaling pathway.

<p>(A) Ingenuity network based on the clustered genes is centered on IFNβ. (B) Expression levels of <i>Ifnb</i> (top) and <i>Rsad2</i> (bottom) in BMDMs infected with the indicated strains of <i>T. gondii</i> for 20 h as determined by RNA sequencing. (C) Secretion of IFNβ protein by BMDMs into culture supernatants after infection with the indicated strains was detected 24 h post-infection by ELISA. (D) BMDMs were infected with indicated <i>Toxoplasma</i> strains for 24 h, and subsequently qPCR was used to detect <i>Ifnb1</i>. Relative expression levels were calculated by normalizing against actin expression. (E) BMDMs were infected with COUGAR and RNA isolated at the indicated time points. qPCR was used to detect <i>Ifnb1</i>. (F–H) Wild-type, IRF3, IRF7 and IRF3/IRF7 knockout immortalized macrophages (F), Unc93b1 triple-deficient mutant (3 d) and MyD88/TRIF double knockout immortalized macrophages (G), or wild-type and RIG-I knockout MEFs (H) were infected with COUGAR and qPCR was used to detect <i>Ifnb1</i>, <i>Rsad2</i> and <i>actin</i> expression levels. Data is representative of three (C–D) or two (E–H) experiments yielding similar results.