FIG. 1.

Quantitation of HGE agent DNA by competitive PCR with primers specific for a 250-bp 16S rRNA target of the HGE agent and a 549-bp competitive target containing an irrelevant 504-bp internal B. burgdorferi ospA segment. Fivefold decreasing amounts (from 1 pg/μl to 0.04 fg/μl) of competitor (top row, 549 bp) were added to a constant amount of HGE agent target DNA (bottom row, 250 bp). The PCR mixtures were amplified for 40 cycles, and the products were resolved on a 1.6% agarose gel stained with ethidium bromide. When competitor and target band intensities were equivalent, the amount of target DNA was presumed to equal the known amount of competitor DNA.