An evolution of Nanopore next-generation sequencing technology: implications for medical microbiology and public health.

Next-generation sequencing has evolved as a powerful tool, with applications that extend from diagnosis to public health surveillance and outbreak investigations. Short-read sequencing, using primarily Illumina chemistry, has been the prevailing approach. Single-molecule sensing and long-read sequencing using Oxford Nanopore Technologies (ONT) has witnessed a breakthrough in the evolution of the technology, performance, and applications in the past few years. In this issue of the Journal of Clinical Microbiology, Bogaerts et al. (https://doi.org/10.1128/jcm.01576-23) describe the utility of the latest ONT sequencing technology, the R10.4.1, in bacterial outbreak investigations. The authors demonstrate that ONT R10.4.1 technology can be comparable to Illumina sequencing for single-nucleotide polymorphism-based phylogeny. The authors emphasize that the reproducibility between ONT and Illumina technologies could facilitate collaborations among laboratories utilizing different sequencing platforms for outbreak investigations.

Retrospective monkeypox virus (MPXV) surveillance among male users of I Want The Kit in Maryland, United States.

Retrospective surveillance leveraging male rectal swab sample remnants from I Want The Kit from July 2021 through October 2023, identified one symptomatic and one asymptomatic mpox case at the peak of transmission in 2022. Although sporadic cases continue to be reported in Maryland, additional asymptomatic cases were not identified in this leveraged surveillance.

Multi-center evaluation of the Research Use Only NeuMoDx monkeypox virus (MPXV) fully automated real-time PCR assay.

The mpox outbreak, caused by monkeypox virus (MPXV), accelerated the development of molecular diagnostics. In this study, we detail the evaluation of the Research Use Only (RUO) NeuMoDx MPXV assay by multiple European and US sites. The assay was designed and developed by Qiagen for the NeuMoDx Molecular Systems. Primers and probes were tested for specificity and inclusivity in silico. The analytical sensitivity of the assay was determined by testing dilutions of synthetic and genomic MPXV DNA. A total of 296 clinical samples were tested by three sites; the Johns Hopkins University (US), UZ Gent (Belgium, Europe), and Hospital Universitario San Cecilio (Spain, Europe). The analytical sensitivity of the assay was 50 copies/mL for both clades I and II. The assay showed 100% in silico identity for 80 clade I and 99.98% in silico identity for 5,162 clade II genomes. Clade II primers and probes showed 100% in silico specificity; however, identity of at least one of the two sets of clade I primers and probes with variola, cowpox, camelpox, and vaccinia viruses was noticed. The clinical validation showed sensitivity of 99.21% [95% confidence interval (CI): 95.66-99.98%] and specificity of 96.64% (95% CI: 91.62-99.08%) for lesion swab samples. The NeuMoDx MPXV Test shows acceptable analytical and clinical performance. The assay improves the laboratory's workflow as it consolidates nucleic acid extraction, PCR, data analysis, and interpretation and can be interfaced. The Test Strip can differentiate clades I and II, which has important laboratory safety implications. IMPORTANCE: In this manuscript, we provide detailed in silico analysis and clinical evaluation of the assay using a large cohort of clinical samples across three academic centers in Europe and the United States. Because the assay differentiates MPXV clades I and II, this manuscript is timely due to the current need to rule out the regulated clade I by diagnostic clinical laboratories. In December 2023, and due to first report of cases of sexually transmitted clade I infections in the Democratic Republic of the Congo, when generic assays that do not differentiate the clades are used, samples are considered regulated. The assay meets the need of full automation and has a marked positive impact on the laboratory workflow.

Reduced control of SARS-CoV-2 infection associates with lower mucosal antibody responses in pregnancy.

Pregnant patients are at greater risk of hospitalization with severe COVID-19 than non-pregnant people. This was a retrospective observational cohort study of remnant clinical specimens from patients who visited acute care hospitals within the Johns Hopkins Health System in the Baltimore, MD-Washington DC, area between October 2020 and May 2022. Participants included confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected pregnant people and matched non-pregnant people (the matching criteria included age, race/ethnicity, area deprivation index, insurance status, and vaccination status to ensure matched demographics). The primary dependent measures were clinical COVID-19 outcomes, infectious virus recovery, viral RNA levels, and mucosal anti-spike (S) IgG titers from upper respiratory tract samples. A total of 452 individuals (117 pregnant and 335 non-pregnant) were included in the study, with both vaccinated and unvaccinated individuals represented. Pregnant patients were at increased risk of hospitalization (odds ratio [OR] = 4.2; confidence interval [CI] = 2.0-8.6), intensive care unit admittance (OR = 4.5; CI = 1.2-14.2), and being placed on supplemental oxygen therapy (OR = 3.1; CI = 1.3-6.9). Individuals infected during their third trimester had higher mucosal anti-S IgG titers and lower viral RNA levels (P < 0.05) than those infected during their first or second trimesters. Pregnant individuals experiencing breakthrough infections due to the Omicron variant had reduced anti-S IgG compared to non-pregnant patients (P < 0.05). The observed increased severity of COVID-19 and reduced mucosal antibody responses particularly among pregnant participants infected with the Omicron variant suggest that maintaining high levels of SARS-CoV-2 immunity through booster vaccines may be important for the protection of this at-risk population.IMPORTANCEIn this retrospective observational cohort study, we analyzed remnant clinical samples from non-pregnant and pregnant individuals with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections who visited the Johns Hopkins Hospital System between October 2020 and May 2022. Disease severity, including intensive care unit admission, was greater among pregnant than non-pregnant patients. Vaccination reduced recovery of infectious virus and viral RNA levels in non-pregnant patients, but not in pregnant patients. In pregnant patients, increased nasopharyngeal viral RNA levels and recovery of infectious virus were associated with reduced mucosal IgG antibody responses, especially among women in their first trimester of pregnancy or experiencing breakthrough infections from Omicron variants. Taken together, this study provides insights into how pregnant patients are at greater risk of severe COVID-19. The novelty of this study is that it focuses on the relationship between the mucosal antibody response and its association with virus load and disease outcomes in pregnant people, whereas previous studies have focused on serological immunity. Vaccination status, gestational age, and SARS-CoV-2 omicron variant impact mucosal antibody responses and recovery of infectious virus from pregnant patients.

Quality control data management with unity real-time in molecular virology.

INTRODUCTION: Quality control (QC) is one component of an overarching quality management system (QMS) that aims at assuring laboratory quality and patient safety. QC data must be acceptable prior to reporting patients' results. Traditionally, QC statistics, records, and corrective actions were tracked at the Johns Hopkins Molecular Virology Laboratory using Microsoft Excel. Unity Real-Time (UnityRT), a QMS software (Bio-Rad Laboratories), which captures and analyzes QC data by instrument and control lot per assay, was implemented and its impact on the workflow was evaluated. The clinical utility of real-time QC monitoring using UnityRT is highlighted with a case of subtle QC trending of HIV-1 quantitative control results. METHODS: A comprehensive workflow analysis was performed, with a focus on Epstein Barr Virus (EBV) and BKV quantitative viral load testing (Roche cobas 6800). The number of QC steps and time to complete each step were assessed before and after implementing UnityRT. RESULTS: Our assessment of monthly QC data review revealed a total of 10 steps over 57 min when using Microsoft Excel, versus 6 steps over 11 min when using UnityRT. HIV-1 QC monitoring revealed subtle trending of the low positive control above the mean from November to December 2022, correlating with a change in the reagent kit lot. This associated with a shift in patients' results from positives below the lower limit of quantification to positives between 20 and 100 copies/mL. CONCLUSIONS: UnityRT consolidated QC analyses, monitoring, and tracking corrective actions. UnityRT was associated with significant time savings, which along with the interfaced feature of the QC capture and data analysis, have improved the workflow and reduced the risk of laboratory errors. The HIV-1 case revealed the value of the real-time monitoring of QC.

Invasive Fungal Infections in Inpatient Solid Organ Transplant Recipients With COVID-19: A Multicenter Retrospective Cohort.

BACKGROUND: The prevalence and outcomes of COVID-19-associated invasive fungal infections (CAIFIs) in solid organ transplant recipients (SOTRs) remain poorly understood. METHODS: A retrospective cohort study of SOTRs with COVID-19 admitted to 5 hospitals within Johns Hopkins Medicine was performed between March 2020 and March 2022. Cox regression multilevel mixed-effects ordinal logistic regression was used. RESULTS: In the cohort of 276 SOTRs, 22 (8%) developed IFIs. The prevalence of CAIFIs was highest in lung transplant recipients (20%), followed by recipients of heart (2/28; 7.1%), liver (3/46; 6.5%), and kidney (7/149; 4.7%) transplants. In the overall cohort, only 42 of 276 SOTRs (15.2%) required mechanical ventilation; these included 11 of 22 SOTRs (50%) of the CAIFI group and 31 of 254 SOTRs (12.2%) of the no-CAIFI group. Compared with those without IFIs, SOTs with IFIs had worse outcomes and required more advanced life support (high-flow oxygen, vasopressor, and dialysis). SOTRs with CAIFIs had higher 1-y death-censored allograft failure (hazard ratio 1.65.116.4, P = 0.006) and 1-y mortality adjusting for oxygen requirement (adjusted hazard ratio 1.12.45.1, P < 0.001), compared with SOTRs without CAIFIs. CONCLUSIONS: The prevalence of CAIFIs in inpatient SOTRs with COVID-19 is substantial. Clinicians should be alert to the possibility of CAIFIs in SOTRs with COVID-19, particularly those requiring supplemental oxygen, regardless of their intubation status.

Is It Possible to Test for Viral Infectiousness?: The Use Case of (SARS-CoV-2).

Identifying and managing individuals with active or chronic disease, implementing appropriate infection control measures, and mitigating the spread of the COVID-19 pandemic highlighted the need for tests of infectiousness. The gold standard for assessing infectiousness has been the recovery of infectious virus in cell culture. Using cycle threshold values, antigen testing, and SARS-CoV-2, replication intermediate strands were used to assess infectiousness, with many limitations. Infectiousness can be influenced by host factors (eg, preexisting immune responses) and virus factors (eg, evolution).

Within-host evolutionary dynamics and tissue compartmentalization during acute SARS-CoV-2 infection.

The global evolution of SARS-CoV-2 depends in part upon the evolutionary dynamics within individual hosts with varying immune histories. To characterize the within-host evolution of acute SARS-CoV-2 infection, we sequenced saliva and nasal samples collected daily from vaccinated and unvaccinated individuals early during infection. We show that longitudinal sampling facilitates high-confidence genetic variant detection and reveals evolutionary dynamics missed by less-frequent sampling strategies. Within-host dynamics in both unvaccinated and vaccinated individuals appeared largely stochastic; however, in rare cases, minor genetic variants emerged to frequencies sufficient for forward transmission. Finally, we detected significant genetic compartmentalization of viral variants between saliva and nasal swab sample sites in many individuals. Altogether, these data provide a high-resolution profile of within-host SARS-CoV-2 evolutionary dynamics.IMPORTANCEWe detail the within-host evolutionary dynamics of SARS-CoV-2 during acute infection in 31 individuals using daily longitudinal sampling. We characterized patterns of mutational accumulation for unvaccinated and vaccinated individuals, and observed that temporal variant dynamics in both groups were largely stochastic. Comparison of paired nasal and saliva samples also revealed significant genetic compartmentalization between tissue environments in multiple individuals. Our results demonstrate how selection, genetic drift, and spatial compartmentalization all play important roles in shaping the within-host evolution of SARS-CoV-2 populations during acute infection.

Orthopoxvirus-Specific T-Cell Responses in Convalescent Mpox Patients.

Orthopoxvirus-specific T-cell responses were analyzed in 10 patients who had recovered from Mpox including 7 people with human immunodeficiency virus (PWH). Eight participants had detectable virus-specific T-cell responses, including a PWH who was not on antiretroviral therapy and a PWH on immunosuppressive therapy. These 2 participants had robust polyfunctional CD4+ T-cell responses to peptides from the 121L vaccinia virus (VACV) protein. T-cells from 4 of 5 HLA-A2-positive participants targeted at least 1 previously described HLA-A2-restricted VACV epitope, including an epitope targeted in 2 participants. These results advance our understanding of immunity in convalescent Mpox patients.

Increased circulation of human adenovirus in 2023: an investigation of the circulating genotypes, upper respiratory viral loads, and hospital admissions in a large academic medical center.

IMPORTANCE: The circulation of human adenoviruses (HAdV) increased in 2023. In this manuscript, we show that HAdV-B3 was predominant in 2023 in a cohort characterized by the Johns Hopkins Hospital System. We also show that HAdV-B3 was associated with an increase in viral loads in respiratory samples and provide a correlation with the clinical presentations and outcomes.

Risk Factors for Hospitalization and Effect of Immunosuppression on Clinical Outcomes Among an Urban Cohort of Patients With Mpox.

Background: During the 2022 mpox outbreak most patients were managed as outpatients, but some required hospitalization. Uncontrolled human immunodeficiency virus (HIV) has been identified as a risk factor for severe mpox. Methods: Patients with mpox diagnosed or treated within the Johns Hopkins Health System between 1 June and 15 December 2022 were included. The primary outcome of interest was risk of hospitalization. Demographic features, comorbid conditions, treatment, and clinical outcomes were determined. Results: A total of 353 patients were tested or treated for mpox; 100 had mpox diagnosed or treated (median age, 35.3 years; 97.0% male; 57.0% black and 10.0% Hispanic; 46.0% people with HIV [PWH]). Seventeen patients (17.0%) required hospitalization, 10 of whom were PWH. Age >40 years, race, ethnicity, HIV status, insurance status, and body mass index >30 (calculated as weight in kilograms divided by height in meters squared) were not associated with hospitalization. Eight of 9 patients (88.9%) with immunosuppression were hospitalized. Immunosuppression was associated with hospitalization in univariate (odds ratio, 69.3 [95% confidence interval, 7.8-619.7]) and adjusted analysis (adjusted odds ratio, 94.8 [8.5-1060.1]). Two patients (11.8%) who were hospitalized required intensive care unit admission and died; both had uncontrolled HIV infection and CD4 T-cell counts <50/µL. Median cycle threshold values for the first positive mpox virus sample did not differ between those who were hospitalized and those who were not. Conclusions: Immunosuppression was a significant risk factor for hospitalization with mpox. PWH with CD4 T-cell counts <50/µL are at high risk of death due to mpox infection. Patients who are immunosuppressed should be considered for early and aggressive treatment of mpox, given the increased risk of hospitalization.

Evolution of Influenza A(H3N2) Viruses in 2 Consecutive Seasons of Genomic Surveillance, 2021-2023.

Background: The circulation and the genomic evolution of influenza A(H3N2) viruses during the 2021/2022 and 2022/2023 seasons were studied and associated with infection outcomes. Methods: Remnant influenza A-positive samples following standard-of-care testing from patients across the Johns Hopkins Health System (JHHS) were used for the study. Samples were randomly selected for whole viral genome sequencing. The sequence-based pEpitope model was used to estimate the predicted vaccine efficacy (pVE) for circulating H3N2 viruses. Clinical data were collected and associated with viral genomic data. Results: A total of 121 683 respiratory specimens were tested for influenza at JHHS between 1 September 2021 and 31 December 2022. Among them, 6071 (4.99%) tested positive for influenza A. Of these, 805 samples were randomly selected for sequencing, with hemagglutinin (HA) segments characterized for 610 samples. Among the characterized samples, 581 were H3N2 (95.2%). Phylogenetic analysis of HA segments revealed the exclusive circulation of H3N2 viruses with HA segments of the 3C.2a1b.2a.2 clade. Analysis of a total of 445 complete H3N2 genomes revealed reassortments; 200 of 227 of the 2022/2023 season genomes (88.1%) were found to have reassorted with clade 3C.2a1b.1a. The pVE was estimated to be -42.53% for the 2021/2022 season and 30.27% for the 2022/2023 season. No differences in clinical presentations or admissions were observed between the 2 seasons. Conclusions: The increased numbers of cases and genomic diversity of influenza A(H3N2) during the 2022/2023 season were not associated with a change in disease severity compared to the previous influenza season.

Next-generation sequencing for cytomegalovirus genotypic antiviral resistance testing.

Sanger-based sequencing has long served as the gold standard for detecting cytomegalovirus (CMV) resistance mutations. However, next-generation sequencing (NGS) offers a highly multiplexed and sensitive approach. Clinical implementation of NGS-antiviral resistance testing requires thorough validation. In this issue of the Journal of Clinical Microbiology, M. A. Mallory, W. C. Hymas, K. E. Simmon, M. T. Pyne, et al. (J Clin Microbiol 61:e00829-23, 2023, https://doi.org/10.1128/jcm.00829-23) detail a validation of a targeted NGS-based assay for multiple genomic regions that confer resistance to CMV antivirals and share their bioinformatics analysis and reporting pipeline. This validation can serve as guidance for laboratories wishing to develop similar methodologies.

Evaluating the impact of point-of-care HIV viral load assessment on linkage to care in Baltimore, MD: a randomized controlled trial.

BACKGROUND: Integration of a sensitive point-of-care (POC) HIV viral load (VL) test into screening algorithms may help detect acute HIV infection earlier, identify people with HIV (PWH) who are not virally suppressed, and facilitate earlier referral to antiretroviral therapy (ART), or evaluation for pre-exposure prophylaxis (PrEP). This report describes a randomized clinical trial sponsored by the Centers for Disease Control and Prevention (CDC): "Ending the HIV Epidemic Through Point-of-Care Technologies" (EHPOC). The study's primary aim is to evaluate the use of a POC HIV VL test as part of a testing approach and assess the impact on time to linkage to ART or PrEP. The study will recruit people in Baltimore, Maryland, including patients attending a hospital emergency department, patients attending an infectious disease clinic, and people recruited via community outreach. The secondary aim is to evaluate the performance characteristics of two rapid HIV antibody tests approved by the United States Food and Drug Administration (FDA). METHODS: The study will recruit people 18 years or older who have risk factors for HIV acquisition and are not on PrEP, or PWH who are not taking ART. Participants will be randomly assigned to either the control arm or the intervention arm. Participants randomized to the control arm will only receive the standard-of-care (SOC) HIV screening tests. Intervention arm participants will receive a POC HIV VL test in addition to the SOC HIV diagnostic screening tests. Follow up will consist of an interim phone survey conducted at week-4 and an in-person week-12 visit. Demographic and behavioral information, and oral fluid and blood specimens will be collected at enrollment and at week-12. Survey data will be captured in a Research Electronic Data Capture (REDCap) database. Participants in both arms will be referred for either ART or PrEP based on their HIV test results. DISCUSSION: The EHPOC trial will explore a novel HIV diagnostic technology that can be performed at the POC and provide viral assessment. The study may help inform HIV testing algorithms and contribute to the evidence to support same day ART and PrEP recommendations. TRIAL REGISTRATION: NIH ClinicalTrials.gov NCT04793750. Date: 11 March 2021.

Dissemination and genome characterization of a human adenovirus F41 in a patient with B-Cell lymphoma.

Adenovirus (HAdV) F41 is a common cause of gastroenteritis and has rarely been reported associated with disseminated disease. In this report, an adult patient with a history of ulcerative colitis, cryptogenic cirrhosis, stage III adenocarcinoma, high-grade diffuse large B-cell lymphoma on chemotherapy was diagnosed with disseminated adenovirus infection. HAdV DNA was quantified in stool, plasma, and urine with viral loads of 7, 4, and 3 log10 copies/mL, respectively. The patient's course was rapidly progressive and he passed away 2 days after initiation of antiviral therapy. The patient's infecting virus was characterized as HAdV-F41 by whole genome sequencing.

Accuracy of Expired BinaxNOW Rapid Antigen Tests.

The widespread existence of expired antigen testing kits in households and potential coronavirus outbreaks necessitates evaluating the reliability of these expired kits. Our study examined BinaxNOW COVID-19 rapid antigen tests 27 months postmanufacture and 5 months past their FDA extended expiration dates, using SARS-CoV-2 variant XBB.1.5 viral stock. We conducted testing at two concentrations, the limit of detection (LOD) and 10 times the LOD. One hundred expired and unexpired kits were tested at each concentration for a total of 400 antigen tests. At the LOD (2.32 × 102 50% tissue culture infective dose/mL [TCID50/mL]), both expired and unexpired tests displayed 100% sensitivity (95% confidence interval [CI], 96.38% to 100%), with no statistical difference (95% CI, -3.92% to 3.92%). Similarly, at 10 times the LOD, unexpired tests retained 100% sensitivity (95% CI, 96.38% to 100%), while expired tests exhibited 99% sensitivity (95% CI, 94.61% to 99.99%), demonstrating a statistically insignificant 1% difference (95% CI, -2.49% to 4.49%; P = 0.56). Expired rapid antigen tests had fainter lines than the unexpired tests at each viral concentration. The expired rapid antigen tests at the LOD were only just visible. These findings carry significant implications for waste management, cost efficiency, and supply chain resilience in pandemic readiness efforts. They also provide critical insights for formulating clinical guidelines for interpreting results from expired kits. In light of expert warnings of a potential outbreak of a severity rivaling the Omicron variant, our study underscores the importance of maximizing the utility of expired antigen testing kits in managing future health emergencies. IMPORTANCE The study examining the reliability of expired antigen testing kits in the context of COVID-19 has significant real-world implications. By demonstrating that these expired kits retain their sensitivity in detecting the virus, this work provides evidence that expired kits can still be utilized, reducing waste and optimizing resources in health care systems. These findings are especially crucial in light of potential future coronavirus outbreaks and the need to be prepared. The study's outcomes have the potential to contribute to waste management efforts, cost efficiency, and supply chain resilience, ensuring that diagnostic tests remain readily available for effective public health interventions. Furthermore, it provides critical insights for formulating clinical guidelines on interpreting results from expired kits, enhancing the accuracy of testing outcomes, and supporting informed decision-making. Ultimately, this work holds great importance in maximizing the utility of expired antigen testing kits, safeguarding public health, and enhancing pandemic readiness on a global scale.

Severity outcomes associated with SARS-CoV-2 XBB variants, an observational analysis.

The rapidity with which SARS-CoV-2 XBB variants rose to predominance has been alarming. We used a large cohort of patients diagnosed with Omicron infections between September 2022 and mid-February 2023 to evaluate the likelihood of admission or need for supplemental oxygen in patients infected with XBB variants. Our data showed no significant association between XBB or XBB.1.5 infections and admissions. Older age groups, lack of vaccination, immunosuppression and underlying heart, kidney, and lung disease showed significant associations with hospitalization.

Development of an amplicon-based sequencing approach in response to the global emergence of mpox.

The 2022 multicountry mpox outbreak concurrent with the ongoing Coronavirus Disease 2019 (COVID-19) pandemic further highlighted the need for genomic surveillance and rapid pathogen whole-genome sequencing. While metagenomic sequencing approaches have been used to sequence many of the early mpox infections, these methods are resource intensive and require samples with high viral DNA concentrations. Given the atypical clinical presentation of cases associated with the outbreak and uncertainty regarding viral load across both the course of infection and anatomical body sites, there was an urgent need for a more sensitive and broadly applicable sequencing approach. Highly multiplexed amplicon-based sequencing (PrimalSeq) was initially developed for sequencing of Zika virus, and later adapted as the main sequencing approach for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Here, we used PrimalScheme to develop a primer scheme for human monkeypox virus that can be used with many sequencing and bioinformatics pipelines implemented in public health laboratories during the COVID-19 pandemic. We sequenced clinical specimens that tested presumptively positive for human monkeypox virus with amplicon-based and metagenomic sequencing approaches. We found notably higher genome coverage across the virus genome, with minimal amplicon drop-outs, in using the amplicon-based sequencing approach, particularly in higher PCR cycle threshold (Ct) (lower DNA titer) samples. Further testing demonstrated that Ct value correlated with the number of sequencing reads and influenced the percent genome coverage. To maximize genome coverage when resources are limited, we recommend selecting samples with a PCR Ct below 31 Ct and generating 1 million sequencing reads per sample. To support national and international public health genomic surveillance efforts, we sent out primer pool aliquots to 10 laboratories across the United States, United Kingdom, Brazil, and Portugal. These public health laboratories successfully implemented the human monkeypox virus primer scheme in various amplicon sequencing workflows and with different sample types across a range of Ct values. Thus, we show that amplicon-based sequencing can provide a rapidly deployable, cost-effective, and flexible approach to pathogen whole-genome sequencing in response to newly emerging pathogens. Importantly, through the implementation of our primer scheme into existing SARS-CoV-2 workflows and across a range of sample types and sequencing platforms, we further demonstrate the potential of this approach for rapid outbreak response.

Clinical performance evaluation of the Aptima viral assays for the quantitation of HIV-1, HCV, and HBV in plasma samples.

The clinical performance of the Aptima® HIV-1 Quant Dx, Aptima HCV Quant Dx, and Aptima HBV Quant Dx were evaluated and compared to the Roche cobas HIV-1, HCV, and HBV assays performed on the Roche cobas 6800 system. The Aptima Quant assays exhibited an overall percent agreement of 99.4% for HBV, 98.3% for HCV, and 85.14% for HIV-1. The average log difference between the Aptima and Roche assays was below 0.2 IU (or copies)/mL and the quantitative correlation's (R-squared value (R2)) was between 0.95 and 0.97. The Aptima viral assays demonstrated a high level of quantitative correlation with the Roche cobas assays for HCV, HBV, and HIV-1.

Comparison of nucleocapsid antigen with strand-specific reverse-transcription PCR for monitoring SARS-CoV-2 infection.

BACKGROUND: Tests that sensitively detect the presence of actively replicating SARS-CoV-2 may improve patient care by allowing the safe and timely discontinuation of isolation. Correlates of active replication include nucleocapsid antigen and virus minus-strand RNA. METHODS: Qualitative agreement of the DiaSorin LIAISON SARS-CoV-2 nucleocapsid antigen chemiluminescent immunoassay (CLIA) with minus-strand RNA was determined using 402 upper respiratory specimens from 323 patients previously tested using a laboratory-developed SARS-CoV-2 strand-specific RT-qPCR. Nucleocapsid antigen levels, minus-strand and plus-strand cycle threshold values, as well as virus culture, were used to evaluate discordant specimens. Receiver operating characteristic curves were also used to identify virus RNA thresholds for active replication, including values harmonized to the World Health Organization International Standard. RESULTS: Overall agreement was 92.0% [95% confidence interval (CI): 89.0 - 94.5], positive percent agreement was 90.6% (95% CI: 84.4 - 95.0), and negative percent agreement was 92.8% (95% CI: 89.0 - 95.6). The kappa coefficient was 0.83 (95% CI: 0.77 - 0.88). Discordant specimens contained low levels of nucleocapsid antigen and minus-strand RNA. 84.8% (28/33) were negative by culture. Sensitivity-optimized plus-strand RNA thresholds for active replication were 31.6 cycles or 3.64 log10 IU/mL; resulting in 100.0% sensitivity (95% CI: 97.6 to 100.0) and 55.9 specificity (95% CI: 49.7 to 62.0). CONCLUSIONS: Detection of nucleocapsid antigen by CLIA performs equivalently to minus-strand detection via strand-specific RT-qPCR, though these methods may overestimate replication-competent virus compared to culture. Careful implementation of biomarkers for actively replicating SARS-CoV-2 has the potential to inform infection control decision-making and patient management.