Comparison of two quantitative real-time CMV-PCR tests calibrated against the 1st WHO international standard for viral load monitoring of renal transplant patients

Disparities in Access to Valganciclovir Cytomegalovirus Prophylaxis in High-Risk African American Kidney Transplant Patients

BACKGROUND

While access and outcomes disparities for African American (AA) kidney transplant recipients are documented, there are limited studies assessing medication access disparities in transplantation. Cytomegalovirus (CMV) causes severe complications for transplant recipients, and we aimed to understand differences in access to CMV prophylaxis valganciclovir and its impact on CMV infection rates in AA transplant recipients.

METHODS

This single-center, retrospective longitudinal cohort study examined high-risk (CMV serostatus D+/R-) adult kidney transplant recipients between June 1, 2010, and May 31, 202, through EMR abstraction. Standard univariate comparative statistics were employed alongside binary logistic regression for multivariable modeling.

RESULTS

During the 10 year period, 418 kidney transplant recipients were included, with 179 (42.8%) identified as AA and 239 as non-AA. There were significant differences in mean age (p = 0.001) and private versus Medicaid insurance status (p < 0.001). AAs experienced higher death-censored graft loss rates (10.6% AA vs. 5.0% non-AA, p = 0.031). CMV infection rate, opportunistic infection rate, leukopenia incidence, and death did not differ significantly between AA and non-AA patients. AA patients were 42% less likely to receive valganciclovir out-of-pocket cost assistance compared to non-AA patients (OR 0.58, [0.379-0.892], p = 0.013). When incorporating age, Medicaid status, and donor marginality in a multivariable model, the impact of AA race on utilizing assistance programs became statistically non-significant (OR 0.70, [0.448-1.094], p = 0.118).

CONCLUSIONS

AAs were significantly less likely to leverage assistance programs or utilize personal resources to access valganciclovir. This disparity was partially explained by age, insurance status, and donor type. Despite this, CMV infection rates were similar between AA and non-AA cohorts.

High burden of CMV infections after simultaneous pancreas-kidney transplantation-a nationwide cohort study

Cytomegalovirus (CMV) infections remain a common problem after solid-organ transplantation. We characterized the burden of CMV infections, and adverse events of CMV prophylaxis after simultaneous pancreas-kidney transplantation (SPK). We included all SPK patients (n = 236) since 2010 in our country. Immunosuppression was ATG, tacrolimus, mycophenolate, and steroids. Valganciclovir prophylaxis was given to all CMV D+/R- patients for six months, and to seropositive SPK patients for three months since February 2019. CMV DNAemia was monitored with quantitative PCR from plasma. Among D+/R- SPK recipients, post prophylaxis CMV infection was detected in 41/60 (68%) during follow-up. In seropositive SPK recipients with no prophylaxis, CMV infection was detected in 53/95 (56%), vs. 28/78 (36%) in those who received 3 months of prophylaxis (P = 0.01). CMV was symptomatic in 35 (15%) patients, of which 10 required hospitalization. Mean duration of viremia was 28 days (IQR 21-41). Leukopenia was detected in 63 (46%) of the 138 patients with valganciclovir prophylaxis. 7/122 (6%) of the CMV infections detected were defined as refractory to treatment, and three patients had confirmed ganciclovir resistance. SPK recipients experience a high burden of CMV infections despite CMV prophylaxis. Leukopenia is common during valganciclovir prophylaxis.

Amplicon size and non-encapsidated DNA fragments define plasma cytomegalovirus DNA loads by automated nucleic acid testing platforms: A marker of viral cytopathology?

Management of cytomegalovirus (CMV) in transplant patients relies on measuring plasma CMV-loads using quantitative nucleic acid testing (QNAT). We prospectively compared the automated Roche-cobas®6800-CMV and Roche-CAP/CTM-CMV with laboratory-developed Basel-CMV-UL54-95bp, and Basel-CMV-UL111a-77bp. Roche-cobas®6800-CMV and Roche-CAP/CTM-CMV were qualitatively concordant in 142/150 cases (95%). In-depth comparison revealed higher CMV-loads of the laboratory-developed assay and correlated with smaller amplicon size. After calibration to the 1.WHO-approved CMV international standard, differences were reduced but remained significant. DNase-I pretreatment significantly reduced CMV-loads for both automated Roche-CAP/CTM-CMV and Roche-cobas®6800-CMV assays, whereby 90% and 95% of samples became undetectable. DNase-I pretreatment also reduced CMV-loads quantified by Basel-CMV-UL54-95bp and Basel-CMV-UL111a-77bp, but remaining detectable in 20% and 35%, respectively. Differences were largest for 110 samples with low-level CMV-DNAemia being detectable but not-quantifiable by Roche-cobas®6800-CMV, whereby the smaller amplicon sizes yielded higher viral loads for concordant positives. We conclude that non-encapsidated fragmented CMV-DNA is the major form of plasma CMV-loads also measured by fully-automated platforms. Amplicons of <150 bp and calibrators are needed for reliable and commutable QNAT-results. We hypothesize that non-encapsidated fragmented CMV-DNA results from lysis of CMV-replicating cells and represent a direct marker of viral cell damage, which contribute to delayed viral load responses despite effective antivirals.

Comparing cytomegalovirus diagnostics by cell culture and quantitative nucleic acid testing in broncho-alveolar lavage fluids

Many clinical laboratories have replaced virus isolation in cell-culture (VIC) for cytomegalovirus (CMV) by quantitative-nucleic-acid testing (QNAT), rendering clinically relevant CMV-replication difficult to distinguish from CMV-shedding or latent infection. We compared direct VIC in 1109 consecutive bronchoalveolar lavage fluids (BALFs) and a well-validated CMV-QNAT (Basel-CMV-UL111a-77bp). In the retrospective Group 1 (N = 694) and Group 2 (N = 303), CMV-QNAT was performed within 48 h from 2-fold and 10-fold concentrated total nucleic acid (TNA) eluates, respectively. In Group 3 (N = 112), 2-fold and 10-fold concentrated TNA eluates were prospectively analyzed in parallel to VIC. CMV was detected by VIC in 79 of 694 (11%) and 26 of 303 (9%) of Groups 1 and 2, but in 114 of 694 (16%) and 57 of 303 (17%) by CMV-QNAT, respectively. Median CMV loads were significantly higher in VIC-positive than in VIC-negative BALF. The likelihood for CMV detection by VIC was 85% for BALF CMV- loads >4 log10 copies/ml. In the prospective Group 3, CMV was detected by VIC in 10 of 112 (9%), and in 14 of 112 (13%) and 20 of 112 (18%) by CMV-QNAT, when using 2-fold and 10-fold concentrated TNA eluates, respectively. Notably, CMV was undetectable by CMV-QNAT in 10 VIC-positive cases of Groups 1 and 2, but in none of Group 3. We conclude that CMV-QNAT can be adopted to BALF diagnostics but requires several careful steps in validation. CMV-QNAT loads >10 000 copies/ml in BALF may indicate significant CMV replication as defined by VIC, if short shipment and processing procedures can be guaranteed. Discordance of detecting CMV in time-matched plasma samples emphasises the role of local pulmonary CMV replication, for which histopathology remains the gold standard of proven CMV pneumonia.

The burden of cytomegalovirus infection remains high in high-risk kidney transplant recipients despite six-month valganciclovir prophylaxis

Cytomegalovirus continues to be a concern after transplantation despite prophylaxis regimens. Our aim was to analyse post-prophylaxis primary cytomegalovirus infections among kidney transplant recipients after 6-month valganciclovir prophylaxis and to determine the usefulness of surveillance after prophylaxis. Data from all cytomegalovirus D+/R- kidney transplant recipients from January 2004 to October 2018 at our center who received 6-month prophylaxis with valganciclovir were retrospectively analysed (N = 481). Detailed analyses were performed for 136 patients who were monitored every 2-4 weeks for DNAemia after the discontinuation of prophylaxis. Post-prophylaxis primary cytomegalovirus infection occurred in 182/481 (38%) patients median 264 days after transplantation (IQR: 226-367) and median 84 days after the end of prophylaxis (IQR: 46-187). In 49% patients, cytomegalovirus infection occurred over 3 months after the end of prophylaxis. Cytomegalovirus infection was not associated with lower patient or graft survival and no independent risk factors for infection were found. From patients monitored closely, 71/136 (52%) patients developed post-prophylaxis primary cytomegalovirus infection. Altogether, 52/136 (38%) patients were diagnosed with probable post-prophylaxis cytomegalovirus disease and 19/136 (14%) patients had asymptomatic CMV infection. Recurrent infection occurred in 38/71 (39%) patients. The incidence of post-prophylaxis primary cytomegalovirus infection among D+/R- kidney transplant recipients remains high despite 6-month prophylaxis. Surveillance after prophylaxis was challenging as a considerable portion of the infections occurred late and already symptomatic.

Comparison of Two Commercial Platforms and a Laboratory-Developed Test for Detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) RNA

Mitigation of the ongoing coronavirus disease 2019 (COVID-19) pandemic requires reliable and accessible laboratory diagnostic services. In this study, the performance of one laboratory-developed test (LDT) and two commercial tests, cobas SARS-CoV-2 (Roche) and Amplidiag COVID-19 (Mobidiag), were evaluated for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in respiratory specimens. A total of 183 specimens collected from suspected COVID-19 patients were studied with all three methods to compare their performance. In relation to the reference standard, which was established as the result obtained by two of the three studied methods, the positive percent agreement was highest for the cobas test (100%), followed by the Amplidiag test and the LDT (98.9%). The negative percent agreement was lowest for the cobas test (89.4%), followed by the Amplidiag test (98.8%), and the highest value was obtained for the LDT (100%). The dilution series of positive specimens, however, suggests significantly higher sensitivity for the cobas assay in comparison with the other two assays, and the low negative percent agreement value may be due to the same reason. In general, all tested assays performed adequately. Clinical laboratories need to be prepared for uninterrupted high-throughput testing during the coming months to mitigate the pandemic. To ensure no interruption, it is critical that clinical laboratories maintain several simultaneous platforms in their SARS-CoV-2 nucleic acid testing.

Evaluation of four commercial extraction-quantification systems to monitor EBV or CMV viral load in whole blood

BACKGROUND

Measurement of cytomegalovirus (CMV) and Epstein-Barr virus (EBV) viral loads is commonly used to monitor posttransplant patients. Two new systems (eMAG/eSTREAM and Versant/kPCR) have been recently commercialized.

OBJECTIVES

To evaluate the performance of four systems to quantify CMV and EBV in whole blood.

STUDY DESIGN

Three extraction and real-time PCR amplification systems: m2000SP/RT (M2000), eMAG/eSTREAM (EMAG), and Versant/kPCR (KPCR) were compared with our routine system Qiasymphony/RGQ (QS/RGQ). The 4 systems were tested using 3 dilutions in triplicate according to the WHO international standard (WHO-IS) for intra-assay reproducibility; 56 whole blood samples (24 patients, 4 follow-ups) for CMV and 45 samples (27 patients, 3 follow-ups) for EBV.

RESULTS

For CMV, the mean of the WHO-IS (expected value: 4.7 Log IU/ml) was: QS/RGQ=4.84, M2000=4.61, EMAG=4.33, and KPCR=4.79. One patient (10 samples) presented a major underquantification by QS/RGQ. Of the 46 remaining samples, 41 were quantified with QS/RGQ, 43 with M2000, 33 with EMAG and 24 with KPCR. For EBV, the mean of the WHO-IS was: QS/RGQ=4.70, M2000=4.61, EMAG=4.62, and KPCR=4.57. Among the 45 samples, 43 were quantified with QS/RGQ, 39 with M2000, 40 with EMAG and 32 with KPCR.

CONCLUSION

The results obtained with the WHO-IS were very good. The results of patients' samples were well correlated with the announced sensitivity of each system. The elevated threshold of the KPCR CMV assay may be problematic for the follow-up of highly immunocompromised patients who require early introduction of treatment.

Evaluation of cellulose pads as a method to detect cytomegalovirus DNA in neonatal urine

Background Several approaches exist to screen neonates for congenital cytomegalovirus infection. We here describe a new method using cellulose pads for urine collection and its evaluation in an experimental and a clinical setting. Methods We systematically tested the effect of storage duration of the pads after exposure to cytomegalovirus-positive urine, meconium contamination and specimen handling on the cytomegalovirus load and the detection rate. Further, the method was tested in clinical practice in a cohort of 500 neonates. Results Following exposure of urine pads with cytomegalovirus-positive urine, the viral load decreased after 15 min, 12 h, 24 h, and 7 days to 63.2%, 42.1%, 31.6%, and 9.3% of the baseline value. Cytomegalovirus detection rate after seven days was 100%. Contamination with meconium resulted in a comparable reduction of the viral load. The detection rate for dried urine pads after seven days was 93.3%. In clinical practice, urine collection from pads was successful in 73.6% by the first attempt and in 26.4% by the second attempt. Conclusions Urine collection using cellulose pads seems feasible regardless of a reduction of the cytomegalovirus load due to exposure to the pad itself or to meconium. Drying of the exposed urine pad should be avoided.

Comparison of two commercial quantitative PCR assays and correlation with the first WHO International Standard for human CMV

Comparability between CMV assays could be facilitated by the first WHO International Standard for human CMV (standard). Standard dilutions were submitted to nucleic acid extraction with Versant kPCR Molecular systems SP or MagNA Pure LC System followed by the kPCR PLX™ CMV DNA (kPCR) or the CMV R-gene™ assay (R-gene), respectively; 139 clinical specimens were tested. Both assays correlated well with the standard (R² > 0.96) and a matrix effect was observed. Quantitative results correlated reasonably between both assays for whole blood (R² = 0.79) and well for other specimen types (R² = 0.93). Quantification differences were within one log₁₀ of the averaged log₁₀ results for 25/27 blood specimens and for 32/33 other specimens. Calibration to the standard did not increase this percentage. In conclusion, results of both assays showed reasonable correlation with each other and good correlation with the standard. Calibration to the standard did not improve comparability of quantitative results.

Quantification of BK Virus Standards by Quantitative Real-Time PCR and Droplet Digital PCR Is Confounded by Multiple Virus Populations in the WHO BKV International Standard

BACKGROUND

The WHO recently released a BK virus (BKV) international standard. This study evaluated the WHO international standard and commercially available BKV standards by quantitative real-time PCR (qPCR) and droplet digital PCR (ddPCR).

METHODS

WHO, Exact Diagnostics, Acrometrix, and Zeptometrix BKV standards were tested by qPCR and ddPCR. Two preparations of NIST BKV clones were also tested. Nucleic acid was extracted with the Roche MP96 and MPLC, followed by quantification in duplicate. To resolve discrepancies, we sequenced the WHO and NIST materials.

RESULTS

Manufacturers' expected copies/mL were close to WHO IU/mL: linear regression of qPCR data revealed 1.12 Exact copies/IU, 0.76 Acrometrix copies/IU, and 0.70 Zeptometrix copies/IU. For ddPCR, similar concentrations were measured when either the VP1 region or the T region was targeted, and concentrations were almost 2-fold higher when both regions were targeted simultaneously. ddPCR results for the VP1 and T regions were similar for all commercial standards, but targeting the T region of the WHO standard led to a 4-fold lower result than the VP1 region. Next-generation sequencing revealed no primer or probe mismatches. However, large differences in coverage across the WHO standard and junctional reads were observed, indicating subpopulations of the WHO standard with deletions in the T region.

CONCLUSIONS

BKV standards showed concordance among providers, but the WHO standard contains subpopulations of viruses with various deletions in the T region. PCR results will vary depending on which region of the WHO standard is targeted.

Blood transfusion and breast milk transmission of cytomegalovirus in very low-birth-weight infants: a prospective cohort study

IMPORTANCE

Postnatal cytomegalovirus (CMV) infection can cause serious morbidity and mortality in very low-birth-weight (VLBW) infants. The primary sources of postnatal CMV infection in this population are breast milk and blood transfusion. The current risks attributable to these vectors, as well as the efficacy of approaches to prevent CMV transmission, are poorly characterized.

OBJECTIVE

To estimate the risk of postnatal CMV transmission from 2 sources: (1) transfusion of CMV-seronegative and leukoreduced blood and (2) maternal breast milk.

DESIGN, SETTING, AND PARTICIPANTS

A prospective, multicenter birth-cohort study was conducted from January 2010 to June 2013 at 3 neonatal intensive care units (2 academically affiliated and 1 private) in Atlanta, Georgia. Cytomegalovirus serologic testing of enrolled mothers was performed to determine their status. Cytomegalovirus nucleic acid testing (NAT) of transfused blood components and breast milk was performed to identify sources of CMV transmission. A total of 539 VLBW infants (birth weight, ≤ 1500 g) who had not received a blood transfusion were enrolled, with their mothers (n = 462), within 5 days of birth. The infants underwent serum and urine CMV NAT at birth to evaluate congenital infection and surveillance CMV NAT at 5 additional intervals between birth and 90 days, discharge, or death.

EXPOSURES

Blood transfusion and breast milk feeding.

MAIN OUTCOMES AND MEASURES

Cumulative incidence of postnatal CMV infection, detected by serum or urine NAT.

RESULTS

The seroprevalence of CMV among the 462 enrolled mothers was 76.2% (n = 352). Among the 539 VLBW infants, the cumulative incidence of postnatal CMV infection at 12 weeks was 6.9% (95% CI, 4.2%-9.2%); 5 of 29 infants (17.2%) with postnatal CMV infection developed symptomatic disease or died. A total of 2061 transfusions were administered among 57.5% (n = 310) of the infants; none of the CMV infections was linked to transfusion, resulting in a CMV infection incidence of 0.0% (95% CI, 0.0%-0.3%) per unit of CMV-seronegative and leukoreduced blood. Twenty-seven of 28 postnatal infections occurred among infants fed CMV-positive breast milk (12-week incidence, 15.3%; 95% CI, 9.3%-20.2%).

CONCLUSIONS AND RELEVANCE

Transfusion of CMV-seronegative and leukoreduced blood products effectively prevents transmission of CMV to VLBW infants. Among infants whose care is managed with this transfusion approach, maternal breast milk is the primary source of postnatal CMV infection.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00907686.