Are We There Yet? Impact of the First International Standard for Cytomegalovirus DNA on the Harmonization of Results Reported on Plasma Samples

Preiksaitis, Jutta K.; Hayden, Randall T.; Tong, Yupin; Pang, Xiaoli; Fryer, Jacqueline F.; Heath, Alan; Cook, Linda; Petrich, Astrid; Yu, Brian; Caliendo, Angela M.

doi:10.1093/cid/ciw370

Cited by 124 publications

(92 citation statements)

References 20 publications

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“…An important limitation of quantitative PCR lies in the interassay and interlaboratory variability of copy number determination, which might impact patient management and clinical decisions. Recently, the WHO released a CMV international standard to overcome the interassay and interlaboratory issues with the aim of reaching an interlaboratory variability of Ͻ0.5 log 10 UI/ml (26). However, the multicentric study conducted with the WHO CMV standard showed interlaboratory variability higher than the expected target of 0.5 log 10 UI/ml, so the route to CMV harmonization and standardization still requires further improvements.…”

Section: Detection Of CMV In Biological Fluidsmentioning

confidence: 99%

Testing for Cytomegalovirus in Pregnancy

et al. 2017

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Congenital cytomegalovirus (CMV) infection represents a relevant cause of deafness and neurological damage in newborns. Intrauterine CMV transmission might result after primary or nonprimary infections, though at different rates (30% versus 0.2%, respectively). At present, a prenatal diagnosis of CMV infection is based mainly on maternal serology, the detection of CMV-DNA in amniotic fluid and fetal blood, and ultrasound (US) and magnetic resonance imaging (MRI). Recent evidences suggest that congenital CMV infection may be an immune-mediated disease and that evaluation of humoral and especially T-cell immunities may improve the overall prenatal diagnosis. This review summarizes the most recent advancements in the diagnosis of maternal and prenatal CMV infections.KEYWORDS human cytomegalovirus, laboratory assays, congenital infections, IgG avidity, CMV-ELISPOT, CMV-QuantiFERON, immunoserology, imaging T he human cytomegalovirus (CMV) is a ubiquitous betaherpesvirus causing morbidity and mortality in immunocompromised patients and congenitally infected fetuses and newborns, resulting in a broad range of disabilities, including sensorineural hearing loss (SNHL), visual impairment, and motor and cognitive deficits. Other transient symptoms of congenital CMV infection (cCMV) may include hepatosplenomegaly, thrombocytopenia, and jaundice. The global prevalence of cCMV has been estimated at 0.7% (1), and fetal CMV transmission may arise from a maternal primary or nonprimary infection. The highest rate of cCMV occurs after primary infections in seronegative mothers (30 to 40%), while nonprimary infections, including CMV reactivations or reinfections, result in cCMV in 0.2 to 2% of cases, suggesting that preconceptional immunity may play a role in preventing intrauterine transmission (2). If the main burden of congenital infections in Europe and North America results from primary infections, then nonprimary infections represent the main cause of cCMV in developing countries or in poor socioeconomical contexts, since the seroprevalences among the resident populations are much higher (3). The severities of infections in neonates and infants are highly variable. It has been estimated that 10 to 15% of congenitally infected neonates are symptomatic at birth, and 40 to 58% of them will experience permanent long-term sequelae. Moreover, 13.5% of children with asymptomatic infections will develop late-onset sequelae, mainly consisting of hearing impairments and neurologic deficits. The effectiveness of antiviral treatment during pregnancy is still debated. Most of the concerns are related to the potential genotoxicity and teratogenicity of the drugs. The clinical benefits of CMV-specific hyperimmune globulin treatment are also disputed, due to discordant results obtained from different studies (4,5).In the last decade, major efforts have been made to improve the early laboratory diagnosis of maternal and fetal infections. Despite these efforts, at present, many countries in the world have not yet adopted a consolidate...

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Section: Detection Of CMV In Biological Fluidsmentioning

confidence: 99%

Testing for Cytomegalovirus in Pregnancy

et al. 2017

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“…A multiinstitution evaluation of the first WHO international standard for CMV DNA demonstrated improved harmonization across assays, though clinically relevant variability remained (13). The factors previously cited to impact BKV NAAT quantification include the nucleic acid extraction method and the design of primers and probes that do not account for variation in BKV genotypes (7)(8)(9).…”

Section: Discussionmentioning

confidence: 99%

“…Similar to the standards previously released for cytomegalovirus (CMV) and Epstein-Barr virus (EBV), the 1st WHO International Standard for BKV is a quantified biological reference material expressed in an international unit (IU). The use of calibrators traceable to the WHO international standard has improved interassay variability for quantifying CMV and EBV DNA and holds promise to also improve that for BKV (13,14).…”

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Calibration of BK Virus Nucleic Acid Amplification Testing to the 1st WHO International Standard for BK Virus

et al. 2017

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Significant interassay variability in the quantification of BK virus (BKV) DNA precludes establishing broadly applicable thresholds for the management of BKV infection in transplantation. The 1st WHO International Standard for BKV (primary standard) was introduced in 2016 as a common calibrator for improving the harmonization of BKV nucleic acid amplification testing (NAAT) and enabling comparisons of biological measurements worldwide. Here, we evaluated the Altona RealStar BKV assay (Altona) and calibrated the results to the international unit (IU) using the Exact Diagnostics BKV verification panel, a secondary standard traceable to the primary standard. The primary and secondary standards on Altona had nearly identical linear regression equations (primary standard, Y ϭ 1.05X Ϫ 0.28, R 2 ϭ 0.99; secondary standard, Y ϭ 1.04X Ϫ 0.26, R 2 ϭ 0.99) and conversion factors (primary standard, 1.11 IU/copy; secondary standard, 1.09 IU/copy). A comparison of Altona with a laboratory-developed BKV NAAT assay in IU/ml versus copies/ml using PassingBablok regression revealed similar regression lines, no proportional bias, and improvement in the systematic bias (95% confidence interval of intercepts: copies/ml, Ϫ0.52 to Ϫ1.01; IU/ml, 0.07 to Ϫ0.36). Additionally, Bland-Altman analyses revealed a clinically significant reduction of bias when results were reported in IU/ml (IU/ml, Ϫ0.10 log 10 ; copies/ml, Ϫ0.70 log 10 ). These results indicate that the use of a common calibrator improved the agreement between the two assays. As clinical laboratories worldwide use calibrators traceable to the primary standard to harmonize BKV NAAT results, we anticipate improved interassay comparisons with a potential for establishing broadly applicable quantitative BKV DNA load cutoffs for clinical practice.

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“…In order to fully establish the commutability of reference materials, large-scale studies using multiple assay platforms in many laboratories are required (6,7). We are undertaking studies to investigate the commutability of the IS for CMV NAT and are collaborating in studies organized by others.…”

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Commutability of the World Health Organization International Standard for Human Cytomegalovirus: Standard or Assay

et al. 2016

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T he development and widespread use of calibrants that are traceable to a higher-order standard enable the results of diagnostic tests performed by different laboratories or at different times to be compared effectively. However, for this to be the case, then it is essential that all reference materials are calibrated appropriately and perform in a similar manner to a patient sample. In 2010, the first WHO international standard (IS) for human cytomegalovirus (CMV) was established as a high-order reference material. Its intended use is to calibrate secondary reference materials used in CMV nucleic acid amplification techniques (NAT) in international units (IU) (1). The CMV IS comprises laboratorygrown virus formulated in a Tris-HCl buffer to enable dilution in the matrix appropriate to the assay (1, 2). This was designed to control for matrix effects and ensure that the standard would be commutable, although at the time of establishment, this was not assessed formally. In their recent study, Jones et al. report on their studies of the commutability of the CMV IS with plasma and whole-blood specimens using the Abbott RealTime CMV assay (3). The authors report that the CMV IS behaves differently when diluted in plasma and whole-blood matrices and extracted using the respective protocols for these matrices, whereas patient samples do not. This matrix effect appeared to reduce the signal for the IS when diluted in whole blood by 0.4 log IU/ml compared with the plasma extraction procedure in this assay platform. The authors conclude that the IS is not commutable.Commutability of a reference standard is dependent not only on the material itself but also on the assay in which it is applied. In particular, in quantitative assays where internal calibrators are included, the nature of these calibrators and the way that they are processed will impact the outcome of the assay (1). In the reported assay, the plasmid-based calibrator used in both plasma and whole-blood processes was calibrated against the IS in plasma alone, rather than in both matrices as recommended (2). This is likely to have contributed to the differing results observed for the patient samples and the IS when diluted in each matrix. If the calibration for the whole-blood process been performed against the IS in whole blood, then the stated conversion factor would have been lower, but comparable with those of other studies (4, 5).In order to fully establish the commutability of reference materials, large-scale studies using multiple assay platforms in many laboratories are required (6, 7). We are undertaking studies to investigate the commutability of the IS for CMV NAT and are collaborating in studies organized by others. The results will contribute to this active debate and clarify the benefit and limitations of specific reference materials in the standardization of assays and data that are designed to assist the clinical management of CMV. Until that time, it will not be possible to fully establish whether the different results observed in the article a...

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Are We There Yet? Impact of the First International Standard for Cytomegalovirus DNA on the Harmonization of Results Reported on Plasma Samples

Abstract: The variability in CMV DNA results reported on individual samples has been reduced by the IS, but ongoing clinically relevant variability persists, preventing meaningful interassay result comparison.

Cited by 124 publications

References 20 publications

Testing for Cytomegalovirus in Pregnancy

Testing for Cytomegalovirus in Pregnancy

Calibration of BK Virus Nucleic Acid Amplification Testing to the 1st WHO International Standard for BK Virus

Commutability of the World Health Organization International Standard for Human Cytomegalovirus: Standard or Assay

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