Expression of β-antigen and <i>bac</i> gene transcription levels in <i>S. agalaciae</i> strains.

<p>Expression of β-antigen in the whole cell lysates of the wild-type strain 168/00 and mutant strains after 2 hrs (lanes 1–3) and 5 hrs of growth (lanes 4–6) was analyzed by SDS-PAGE (Panel A) and western-blotting with labeled human IgA (Panel B). Lanes 1 and 4–strain 168/00; lanes 2 and 5–<i>sak188</i> mutant strain; lanes 3 and 6–<i>sak189/sak188</i> double mutant strain; lane 7–protein ladder (Bio-Rad Laboratories). <i>bac</i> gene transcription levels (Panel C) were assessed by quantitative reverse transcriptase (RT)-PCR. Numbers indicate relative differences (%) in transcription levels of <i>bac</i> gene in mutant strains compared to transcription level of <i>bac</i> gene in wild-type strain. The <i>bac</i> gene transcription level was normalized to the <i>cpn60</i> gene transcription level in each strain. Mean values and standard errors are shown as results of two independent experiments.