(A) Western blot analysis of SslE from (i) whole-cell lysates and (iii) supernatant fractions prepared from UTI89, UTI89sslE, IHE3034, IHE3034sslE, 536, EC958 and MG1655. SslE has a predicted size of approximately 167 kDa. Two major cross-reacting bands of this size were detected (indicated by arrows), possibly representing full-length and processed SslE. No cross-reacting bands were detected in samples prepared from UTI89sslE and IHE3034sslE, demonstrating the specificity of antibody. (ii) Loading control for whole cell lysate samples. The same samples used above were examined by western blot using an OmpA antibody. Similar levels of OmpA were detected in all samples, indicating equivalent loading of total protein. (B) Relative fold-difference of sslE transcript levels of ExPEC strains UTI89, IHE3034, 536, EC958 as determined by qRT-PCR. All mRNA levels were calculated relative to the level of UTI89 sslE mRNA. The relative sslE mRNA levels were consistent with the data observed from the western blot analysis. The data was obtained from three independent experiments; error bars indicate standard deviation.