[Evaluation of the Two Different Real Time Polymerase Chain Reaction Methods Used for BK Virus (BKV) Quantification...

Area of Science:

• Virology
• Transplantation Immunology
• Clinical Diagnostics

Background:

• BK virus (BKV) viral load quantification is critical for managing BKV nephropathy and preventing organ rejection in renal transplant recipients.
• Variability in BKV DNA measurement across different laboratories and real-time PCR methods can affect clinical decision-making.

Purpose of the Study:

• To compare BKV DNA quantification values obtained from two distinct real-time PCR methods in different laboratories.
• To determine the prevalence of BKV genotypes among renal transplant recipients.

Main Methods:

• 150 clinical samples (plasma and urine) from renal transplant patients were analyzed using two different automated nucleic acid extraction and real-time PCR systems (targeting VP-1 and VP-2 gene regions).
• BKV genotyping was performed using multiplex PCR for genotypes I-IV.
• Qualitative and quantitative agreement between the two methods was assessed using Cohen's kappa, linear regression, and Bland-Altman analysis.

Main Results:

• A moderate agreement (ƙ= 0.56) was observed for qualitative BKV detection between the two laboratories.
• Quantitative analysis showed moderate to high correlation for plasma (R²=0.52) and urine (R²=0.88) samples, respectively, but with significant mean differences (-0.29 log10 for plasma, -1.1 log10 for urine).
• Over 70% of samples exhibited a viral load measurement difference greater than 0.5 log10, with only 28.1% within the clinically acceptable range.
• BKV genotype I was most prevalent (81.7%), followed by genotype IV (15.5%). Genotype IV samples showed larger viral load measurement discrepancies.

Conclusions:

• Significant quantitative discrepancies exist between the two real-time PCR methods, potentially leading to incorrect clinical decisions regarding BKV nephropathy management.
• The current lack of standardized BKV quantification hinders reliable cross-laboratory comparisons and clinical interpretation.
• It is recommended that each center consistently use the same BKV testing method until an international standard is optimized and validated.