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Optimization of LipL32 PCR assay for increased sensitivity in diagnosing leptospirosis
Renee L Galloway1, Alex R Hoffmaster1
1Bacterial Special Pathogens Branch, Division of High-Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Atlanta, GA, USA.
Abstract:
Early diagnosis of leptospirosis in humans is critical with regard to initiation of appropriate treatment; however, the gold standard serological test cannot detect antibodies until nearly a week after symptom onset. PCR has been shown to be sensitive and specific in the early phase of leptospirosis. Previously, we developed and validated a TaqMan PCR assay targeting lipL32. We reoptimized and validated this assay using PerfeCTa® qPCR ToughMix®, Low ROX™ (Quanta Biosciences, Gaithersburg, MD, USA). For optimization with the new mix, the final primer concentrations were increased from 0.5 micromol/L to 0.9 micromol/L compared to our previous assay, and the probe concentration increased from 0.1 micromol/L to 0.125 micromol/L. This newly optimized assay resulted in a lower limit of detection and increased diagnostic sensitivity. Here, we present the performance data of the improved assay and describe several clinical cases that were initially negative but tested positive using the optimized assay.
Insights
Early diagnosis of leptospirosis is crucial. An improved PCR assay targeting lipL32 offers higher sensitivity and a lower detection limit for early leptospirosis detection, outperforming traditional serological tests.
Area of Science:
- Infectious Diseases
- Molecular Diagnostics
- Microbiology
Background:
- Early diagnosis of leptospirosis is vital for timely treatment.
- Standard serological tests detect antibodies late, after symptom onset.
- Polymerase Chain Reaction (PCR) shows promise for early leptospirosis detection.
Purpose of the Study:
- To reoptimize and validate a TaqMan PCR assay targeting the lipL32 gene for improved leptospirosis diagnosis.
- To enhance the diagnostic sensitivity and lower the limit of detection of the existing PCR assay.
Main Methods:
- Reoptimization of a previously developed TaqMan PCR assay targeting lipL32.
- Utilized PerfeCTa® qPCR ToughMix®, Low ROX™ for assay validation.
- Adjusted primer concentrations to 0.9 µmol/L and probe concentration to 0.125 µmol/L.
Main Results:
- The optimized PCR assay demonstrated a lower limit of detection.
- Increased diagnostic sensitivity was achieved with the reoptimized assay.
- Several clinical cases initially negative by other methods tested positive with the improved assay.
Conclusions:
- The improved TaqMan PCR assay offers enhanced sensitivity and a lower limit of detection for early leptospirosis diagnosis.
- This optimized assay can aid in the early identification of leptospirosis, even in cases initially missed by other diagnostic methods.
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