Evaluation of a Standardized Laboratory-Developed Assay for Quantification of BK Virus in Renal Transplant Recipients

This study aims to evaluate the clinical performance of an in-house laboratory-developed assay (LDA) calibrated against the first World Health Organization (WHO) international standard for quantification of BK virus (BKV) in recipients of renal transplants.

A total of 83 samples were collected from patients who underwent renal transplantation at Military Hospital 103, Vietnam Military Medical University. BKV loads were measured using an in-house LDA in comparison with the Altona assay on urine and plasma samples.

The limit of detection was established against the first WHO international standard and was estimated to be 135 IU/mL. The intra-assay and interassay coefficients of variation ranged from 0.42% to 1.13% and from 1.71% to 2.47%, respectively. The comparative evaluation of the LDA with the Altona assay on 83 clinical samples showed the diagnostic sensitivity and specificity of the LDA to be 98.04% and 90.62%, respectively. The Kappa value of 0.897 (95% CI, 0.781-0.975) showed a good agreement. For 50 quantitative results obtained by the two assays, excellent agreement and strong correlation were observed by linear regression (r² = 0.95 for all samples), and Passing-Bablok regression analysis was used for method comparisons; the Bland-Altman plot analysis did not show any mean difference between measured values of the two assays for all samples.

The LDA had good analytical and clinical performance for quantification of BKV as compared with the Altona assay. This LDA calibrated against the first WHO international standard could be useful for monitoring BKV replication in recipients of renal transplants in resource-challenged settings.