Genetic and antigenic features of <i>M. agalactiae</i> strain PG2 and NifS mutants used for animal inoculation.

<p>Knock-out mutants NifS1 and NifS2 were generated by transposon mutagenesis in <i>M. agalactiae</i> reference strain PG2 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0093970#pone.0093970-Baranowski1" target="_blank">[18]</a>. (<b>A</b>) Drawing illustrating the NIF locus (grey arrows) in <i>M. agalactiae</i>. Genes are represented according to their orientations on the genome. Transposon insertion sites in NifS mutants are indicated by a vertical bar with a closed circle, an arrow indicate its orientation. The insertion of the transposon in mutant NifS2 occurred within the stop codon of <i>nifS </i><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0093970#pone.0093970-Baranowski1" target="_blank">[18]</a>. The scale is indicated. (<b>B</b>) SDS-PAGE analysis of Triton X-114 soluble materials extracted from cultures of PG2 and NifS mutants followed by Coomassie staining or immunodetection using the PAL97 hyperimmune serum. Molecular weight standards (MW) are in kDa. (<b>C</b>) Characterization of phase variable, Vpma expression profile in <i>M. agalactiae</i> inoculums. Vpma lipoproteins U, V, W, X, Y and Z were detected using specific polyclonal antibodies (see Materials and Methods). A lipoprotein P80 antiserum was used as control. (<b>D</b>) Growth curves of PG2 and NifS mutants in SP4-HS medium. Mycoplasma titers used for inoculations were 10⁷ CFU/ml (left panel) and 10⁵ CFU/ml (right panel). The data are the means of three independent assays. Standard deviations are indicated by error bars.