BK virus (BKV) infection and reactivation increase the risk of BKV-associated nephropathy and allograft failure in immune-compromised individuals;the condition could be managed by reducing immunosuppressive medication. Quantitative polymerase chain reaction (qPCR) screening for BKV has become the standard of care. The 1st World Health Organization International Standard for BKV DNA was introduced in 2016, facilitating standardizing and comparing various BKV qPCR assays. The Korean Association of External Quality Assessment Service (KEQAS) changed the reporting unit of BKV qPCR from log 10 copies/mL to log 10 IU/mL in 2024.This article shares our experience with calculating the conversion factor for copies-to-international units (IU) using standard materials. The conversion factors derived by Real-Q BK Virus Quantification Kit for plasma and urine were 0.48 and 0.19, respectively. The inconsistent performance of two identical nucleic acid extraction instruments was revealed, highlighting one of the various factors contributing to the variability of BKV quantification.We also considered the effects of changing the reporting unit on external quality assessment and standardization in general. Following the change, the KEQAS showed decreased interlaboratory variability. Switching the reporting unit to IU is expected to reduce inter-assay variability, providing each laboratory establishes and uses its conversion factor.

BK virus (BKV) infection and reactivation increase the risk of BKV-associated nephropathy and allograft failure in immune-compromised individuals;the condition could be managed by reducing immunosuppressive medication. Quantitative polymerase chain reaction (qPCR) screening for BKV has become the standard of care. The 1st World Health Organization International Standard for BKV DNA was introduced in 2016, facilitating standardizing and comparing various BKV qPCR assays. The Korean Association of External Quality Assessment Service (KEQAS) changed the reporting unit of BKV qPCR from log 10 copies/mL to log 10 IU/mL in 2024.This article shares our experience with calculating the conversion factor for copies-to-international units (IU) using standard materials. The conversion factors derived by Real-Q BK Virus Quantification Kit for plasma and urine were 0.48 and 0.19, respectively. The inconsistent performance of two identical nucleic acid extraction instruments was revealed, highlighting one of the various factors contributing to the variability of BKV quantification.We also considered the effects of changing the reporting unit on external quality assessment and standardization in general. Following the change, the KEQAS showed decreased interlaboratory variability. Switching the reporting unit to IU is expected to reduce inter-assay variability, providing each laboratory establishes and uses its conversion factor.

BK virus (BKV) infection and reactivation increase the risk of BKV-associated nephropathy and allograft failure in immune-compromised individuals;the condition could be managed by reducing immunosuppressive medication. Quantitative polymerase chain reaction (qPCR) screening for BKV has become the standard of care. The 1st World Health Organization International Standard for BKV DNA was introduced in 2016, facilitating standardizing and comparing various BKV qPCR assays. The Korean Association of External Quality Assessment Service (KEQAS) changed the reporting unit of BKV qPCR from log 10 copies/mL to log 10 IU/mL in 2024.This article shares our experience with calculating the conversion factor for copies-to-international units (IU) using standard materials. The conversion factors derived by Real-Q BK Virus Quantification Kit for plasma and urine were 0.48 and 0.19, respectively. The inconsistent performance of two identical nucleic acid extraction instruments was revealed, highlighting one of the various factors contributing to the variability of BKV quantification.We also considered the effects of changing the reporting unit on external quality assessment and standardization in general. Following the change, the KEQAS showed decreased interlaboratory variability. Switching the reporting unit to IU is expected to reduce inter-assay variability, providing each laboratory establishes and uses its conversion factor.

BK virus (BKV) infection and reactivation increase the risk of BKV-associated nephropathy and allograft failure in immune-compromised individuals;the condition could be managed by reducing immunosuppressive medication. Quantitative polymerase chain reaction (qPCR) screening for BKV has become the standard of care. The 1st World Health Organization International Standard for BKV DNA was introduced in 2016, facilitating standardizing and comparing various BKV qPCR assays. The Korean Association of External Quality Assessment Service (KEQAS) changed the reporting unit of BKV qPCR from log 10 copies/mL to log 10 IU/mL in 2024.This article shares our experience with calculating the conversion factor for copies-to-international units (IU) using standard materials. The conversion factors derived by Real-Q BK Virus Quantification Kit for plasma and urine were 0.48 and 0.19, respectively. The inconsistent performance of two identical nucleic acid extraction instruments was revealed, highlighting one of the various factors contributing to the variability of BKV quantification.We also considered the effects of changing the reporting unit on external quality assessment and standardization in general. Following the change, the KEQAS showed decreased interlaboratory variability. Switching the reporting unit to IU is expected to reduce inter-assay variability, providing each laboratory establishes and uses its conversion factor.

BK virus (BKV) infection and reactivation increase the risk of BKV-associated nephropathy and allograft failure in immune-compromised individuals;the condition could be managed by reducing immunosuppressive medication. Quantitative polymerase chain reaction (qPCR) screening for BKV has become the standard of care. The 1st World Health Organization International Standard for BKV DNA was introduced in 2016, facilitating standardizing and comparing various BKV qPCR assays. The Korean Association of External Quality Assessment Service (KEQAS) changed the reporting unit of BKV qPCR from log 10 copies/mL to log 10 IU/mL in 2024.This article shares our experience with calculating the conversion factor for copies-to-international units (IU) using standard materials. The conversion factors derived by Real-Q BK Virus Quantification Kit for plasma and urine were 0.48 and 0.19, respectively. The inconsistent performance of two identical nucleic acid extraction instruments was revealed, highlighting one of the various factors contributing to the variability of BKV quantification.We also considered the effects of changing the reporting unit on external quality assessment and standardization in general. Following the change, the KEQAS showed decreased interlaboratory variability. Switching the reporting unit to IU is expected to reduce inter-assay variability, providing each laboratory establishes and uses its conversion factor.

Background: Inconclusive SARS-CoV-2 real-time reverse transcription-PCR (rRT-PCR) test results, which are positive for one or more target genes but not all, are problematic in clinical laboratories. In this study, we aimed to investigate the cause and clinical relevance of such inconclusive results. Methods: rRT-PCR was performed using the Allplex 2019-nCoV assay kit (Seegene Inc., Korea) targeting the following three genes: E, RdRp, and N. For all inconclusive test results reported from March to June 2020, the frequency per kit, lot number, specimen type, cycle threshold (Ct) and peak values of the amplification curves, positive target genes, and results of repeated or consecutive tests were analyzed. Results: A total of 43,268 tests were conducted, of which 93 (0.21%) were inconclusive—49 from 11 coronavirus disease 2019 (COVID-19) patients and 44 from non-COVID-19 patients.In COVID-19 patients, the results were inconclusive 11.9 ± 4.7 days after diagnosis and were negative 8.8 ± 5.5 days after the inconclusive results were reported. However, in nonCOVID-19 patients, they were all negative upon retest and 81.8% of them were identified to have yielded in 2 out of 8 lots. The most frequently positive target genes were N (55.4%) in COVID-19 and RdRp (61.2%) in non-COVID-19 patients, respectively. No difference was observed in the Ct or peak values of the amplification curves for inconclusive samples between COVID-19 and non-COVID-19 cases. Conclusion Inconclusive test results should be reported neither positive nor negative. Such results can be reported as inconclusive without retesting in COVID-19 patients; however, they should certainly be confirmed by a retest in non-COVID-19 patients or newly diagnosed cases.

Hu5F9-G4, an immunoglobulin 4 (IgG4) monoclonal humanized antibody targeting CD47, is under active clinical trials as a novel immunotherapeutic for hematologic and solid malignancies and can cause pretransfusion testing interference. In this study, we demonstrate our first experience of Hu5F9-G4 interference with serologic testing and mitigate this interference through multiple platelet alloadsorption. A 69-year-old woman with a history of ureter cancer presented with anemia. On routine blood group typing, the patient showed strong agglutination (4+) with anti-A, A, and B cells. Unexpectedly, antibody screening and identification showed panreactivity to all panel cells, although the autocontrol result was negative. Medical records revealed that she was enrolled in an anti-CD47 clinical trial. To eliminate interference by the drug, we attempted alloadsorption using pooled platelets that were prepared from segments of random single donor platelets. After seven alloadsorption sessions using pooled allogeneic platelets, the ABO discrepancy and panreactivity was resolved. To our knowledge, this is the first demonstration of anti-CD47 interference elimination in Korea.