FIG. 4.

Ovine STEC treatment prevents SLP increase in cultured PBMC. Cell proliferation was measured as the incorporation of tritiated thymidine and expressed as kCPM. Four experimental groups are shown that were treated biweekly with oral doses of 5 × 10¹⁰ CFU bacteria/animal. Two groups received STEC, starting 2 weeks before BLV challenge (pre & post BLV STEC, group 1) or starting 24 h post-BLV challenge (post BLV STEC, group 2) and continuing for 16 weeks post-BLV challenge. Two groups received E. coli K-12 starting at week −2. The infection control group received BLV (BLV no STEC, group 3), and the healthy control group was not challenged with BLV (no BLV, group 4). (A) Data are means ± SEMs of cultures from five sheep. The horizontal broken line indicates the average background proliferation in PBMC cultures prior to BLV challenge. (B) The maximal SLP values were obtained between 4 and 6 weeks post-BLV challenge. Data are median kCPM values per four culture replicates (cross bars) and 95% confidence intervals for medians (boxes). The horizontal dotted line indicates the upper range of SLP in the healthy controls (group 4), and the star indicates a statistically significant difference from this group (P < 0.05). Light stipple indicates the animals that had zero or <10³ CFU/g (low) fecal STEC counts despite STEC treatment, and heavy stipple indicates animals in the untreated group that had >10⁴ CFU/g (high) fecal STEC counts.