Hit validation and summary.

For each hit identified in the primary screens, four redundant siRNA duplexes were tested individually to determine the silencing efficiency by real-time PCR analysis (RT-PCR, % mRNA remaining) and the strength of the observed spreading phenotype (Z-score). In bold are the duplexes conferring a spreading defect (Z-Score >2). Only CSNK1A1 and CSNK2B targeting duplexes display a strict correlation between silencing efficiency and spreading defect phenotype and are therefore specifically involved in L. monocytogenes cell-to-cell spread. The bottom right corner displays the validation summary with 2 ON-target (true) and 5 OFF-target (false) hits.