A real time genotyping PCR assay for polyomavirus BK

Area of Science:

• Virology
• Molecular Biology
• Immunology

Background:

• BK polyomavirus (BKV) is a significant pathogen causing nephropathy in kidney transplant recipients and hemorrhagic cystitis in bone marrow transplant recipients.
• Accurate and rapid identification of BKV genotypes is crucial for managing these post-transplant complications.
• Existing methods for BKV genotyping can be time-consuming and less accessible in clinical settings.

Purpose of the Study:

• To develop and validate rapid, real-time PCR (RT-PCR) assays for differentiating the four major BKV genotypes (BKGT I-IV).
• To establish a sensitive and specific diagnostic tool for BKV genotyping in clinical samples.
• To assess the utility of RT-PCR for detecting BKV double infections.

Main Methods:

• A duplex real-time PCR (RT-PCR) assay was designed targeting the VP1 gene to differentiate the four main BKGT.
• The assay was validated using 212 BKV-positive samples (21 plasma, 191 urine).
• Genotyping results for 55 samples were confirmed by sequencing a specific VP1 gene fragment.

Main Results:

• Highly specific and precise RT-PCR assays were developed with an internal control and a limit of detection of log 3 copies/mL.
• Genotyping was successful for the majority of samples, with 18 samples (8.5%) showing unsuccessful genotyping due to low viral load.
• Sequencing confirmed the genotypes for 46 out of 55 samples and identified double infections in 2 out of 4 samples.

Conclusions:

• The developed RT-PCRs provide a rapid, cost-effective, and sensitive method for detecting and differentiating major BKV genotypes compared to sequencing.
• The assay can effectively detect BKV double infections.
• This validated RT-PCR method is valuable for investigating the clinical significance of BKV infection based on genotype.