<p>Anti-C1q autoantibodies are induced by curli administration or <i>Salmonella</i> Typhimurium infection.</p>

<p><b>(A-B)</b> Mouse serum was assayed using a multiplex Luminex platform and antibodies quantified by mean fluorescence intensity (MFI); only anti-C1q antibodies are shown here, see <a href="plospathogens.org/article/info:doi/10.1371/journal.ppat.1014666#ppat.1014666.s001" target="_blank">S1 Fig</a> for other antigens. 6-8 week old <b>(A)</b> C57BL/6 mice and <b>(B)</b> NZBxW/F1 mice were injected intraperitoneally with curli purified from <i>Salmonella</i> Typhimurium (STm) biofilms, or sterile PBS for controls, weekly for (<b>A</b>) 12 weeks or (<b>B</b>) 5 weeks. <b>(C-F)</b> Anti-C1q antibodies in serum (diluted 1:50) were detected using ELISA, normalized to aliquots of serum from an untreated aged MRL/lpr mouse as a positive control (1:50, top dotted line) and a negative control without serum (bottom dotted line). <b>(C)</b> C57BL/6 mice were injected intraperitoneally with 100 µg curli purified from STm biofilms, 100 µg/kg LPS, 50 µg curli and 50 µg/kg LPS, or PBS for untreated controls, weekly for 3 weeks<b>.

(D)</b> C57BL/6 mice were injected intraperitoneally with 100 µg curli purified from the biofilm of an <i>E. coli</i> isolate from the human microbiome (hEC), an <i>E. coli</i> isolate from the mouse microbiome (mEC), STm biofilms, or PBS for untreated controls, weekly for 4 weeks<b>.</b> (<b>E</b>) 129Sv mice were infected intragastrically with 10⁷ CFU of wild-type (WT) STm strain IR715, the isogenic curli-deficient mutant csgBA, or LB broth for uninfected controls, in two replicate experiments, and Week 6 serum was assayed. <b>(F)</b> C57BL/6 mice were infected intragastrically with 10⁷ CFU of STm <i>spiB</i> or <i>invAspiB</i> mutant, or LB broth for uninfected controls, and monitored for 10 weeks.