Fig 1. L. interrogans 16S rRNA primers offered highest analytical sensitivity.

A) Total RNA samples isolated from cultured spirochetes were converted into cDNA and amplification cycles (cycle threshold or Ct value) of various L. interrogans target genes are assessed in qRT-PCR assays in the presence (gray bars) or absence (black bars) of hamster cDNA. Data represent results from three independent experiments. B) 16S rRNA primers display a high PCR efficiency. L. interrogans cDNA in RNase-free water (320 ng/μL) was serially diluted to tenfold (10⁻¹ to 10⁻⁹) and subjected to qRT-PCR assays using 16S-1 primers. Amplification cycles (left panel) were used to calculate standard curve (middle panel), which indicated detection to 10⁻⁹ dilutions with an amplification efficiency of 91.2%. A melt curve analysis (right panel) showed a melting temperature of 82°C without any non-specific amplification.