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Development and validation of qPCR assay targeting COWP conserved region for sensitive detection and quantification
Hend Okasha1, Hadeer A El-Kalamawy1, Ahmed R Mashaal2
1Biochemistry and Molecular Biology Department, Theodor Bilharz Research Institute, Giza, Egypt.
Background:
Cryptosporidium is a significant food and waterborne protozoan parasite. Molecular diagnosis and quantification play a crucial role in diagnosing infections, as well as in understanding the transmission dynamics. The Cryptosporidium oocyst wall protein (COWP) gene serves as an appropriate target for such assays since it remains conserved uniquely among significant species.
Objective:
The current research focused on developing and validating a sensitive and specific quantitative PCR (qPCR) test targeting a conserved domain of the COWP gene to detect and quantify various Cryptosporidium species.
Methods:
Design of selective degenerate primers on a conserved domain in the major Cryptosporidium spp. COWP gene. A COWP DNA library was constructed using molecular cloning into pET-15b vector to be used as a precursor for a standard curve absolute quantification strategy.
Results:
The designed primers successfully amplified a 311-317 bp product, with specificity tested using melt curve analysis. The slope of the standard curve was -3.279, efficiency of 100.8 %, and R² = 0.95 (p < 0.0001) with LOD equals 9.55 × 10⁴ copies /µL.
Conclusion:
A qPCR assay that is both sensitive and efficient was developed and validated. The method produces a reliable technique of absolute quantitation of Cryptosporidium DNA in samples of unknown quantity, from which infection rates may be estimated accurately.
Insights
A new quantitative PCR (qPCR) test accurately detects and quantifies Cryptosporidium parasite DNA using the COWP gene. This sensitive method aids in diagnosing infections and understanding disease transmission.
Area of Science:
- Molecular biology
- Parasitology
- Infectious disease diagnostics
Background:
- Cryptosporidium is a major food and waterborne protozoan parasite.
- Accurate molecular diagnosis and quantification are vital for infection detection and understanding transmission dynamics.
- The Cryptosporidium oocyst wall protein (COWP) gene is a conserved target for molecular assays.
Purpose of the Study:
- To develop and validate a sensitive and specific quantitative PCR (qPCR) assay.
- To target a conserved domain of the COWP gene for detecting and quantifying diverse Cryptosporidium species.
Main Methods:
- Designed degenerate primers targeting a conserved COWP gene domain.
- Constructed a COWP DNA library using molecular cloning for absolute quantification.
- Utilized a standard curve strategy for quantitative analysis.
Main Results:
- Primers successfully amplified a 311-317 bp product with high specificity confirmed by melt curve analysis.
- Achieved high assay efficiency (100.8%) and linearity (R² = 0.95).
- Established a limit of detection (LOD) of 9.55 × 10⁴ copies/µL.
Conclusions:
- Developed and validated a sensitive and efficient qPCR assay for Cryptosporidium.
- The method provides reliable absolute quantitation of Cryptosporidium DNA.
- Enables accurate estimation of infection rates from unknown sample quantities.
