FIG. 2.

Range of detection. Known amounts of C. pneumoniae DNA (10³ to 10⁻⁶ IFU) were spiked into a constant background of human genomic DNA (1 μg) and assayed by PCR. (A) The first round of amplifications with the outer primer pair demonstrates the ability of the assay to detect as few as 0.1 IFU. (B) The second round of amplifications using the nested primer pair extends this range to 0.001 to 0.0001 IFU. A 100-bp ladder was run (lanes labeled 100) alongside PCR products for size determination.