Quantitative reverse-transcriptase PCR analysis of B. mallei and B. pseudomallei strains. Total RNA was isolated from B. pseudomallei (Bp) DD503 and B. mallei (Bm) ATCC23344, reverse-transcribed to cDNA, and the relative levels of boaA or boaB transcript was determined by qRT-PCR. Each bar represents 4 different samples collected on 2 separate occasions. The Y-axis corresponds to levels of boaA or boaB transcript normalized to recA and the error bars correspond to the standard error. A primer set for Borrelia burgdorferi recA was used as a control to further demonstrate primer specificity (see bars labeled as control). Of note, negative controls in which the reverse transcriptase enzyme was not added to reaction mixtures were included in all experiments and the results were equivalent to the Borrelia burgdorferi controls (data not shown).