Maturation and persistence of the anti-SARS-CoV-2 memory B cell response.

Memory B cells play a fundamental role in host defenses against viruses, but to date, their role has been relatively unsettled in the context of SARS-CoV-2. We report here a longitudinal single-cell and repertoire profiling of the B cell response up to 6 months in mild and severe COVID-19 patients. Distinct SARS-CoV-2 spike-specific activated B cell clones fueled an early antibody-secreting cell burst as well as a durable synchronous germinal center response. While highly mutated memory B cells, including pre-existing cross-reactive seasonal Betacoronavirus-specific clones, were recruited early in the response, neutralizing SARS-CoV-2 RBD-specific clones accumulated with time and largely contributed to the late, remarkably stable, memory B cell pool. Highlighting germinal center maturation, these cells displayed clear accumulation of somatic mutations in their variable region genes over time. Overall, these findings demonstrate that an antigen-driven activation persisted and matured up to 6 months after SARS-CoV-2 infection and may provide long-term protection.

SARS-CoV-2 Omicron BA.1 breakthrough infection drives late remodeling of the memory B cell repertoire in vaccinated individuals.

How infection by a viral variant showing antigenic drift impacts a preformed mature human memory B cell (MBC) repertoire remains an open question. Here, we studied the MBC response up to 6 months after SARS-CoV-2 Omicron BA.1 breakthrough infection in individuals previously vaccinated with three doses of the COVID-19 mRNA vaccine. Longitudinal analysis, using single-cell multi-omics and functional analysis of monoclonal antibodies from RBD-specific MBCs, revealed that a BA.1 breakthrough infection mostly recruited pre-existing cross-reactive MBCs with limited de novo response against BA.1-restricted epitopes. Reorganization of clonal hierarchy and new rounds of germinal center reactions, however, combined to maintain diversity and induce progressive maturation of the MBC repertoire against common Hu-1 and BA.1, but not BA.5-restricted, SARS-CoV-2 Spike RBD epitopes. Such remodeling was further associated with a marked improvement in overall neutralizing breadth and potency. These findings have fundamental implications for the design of future vaccination booster strategies.

Analysis of mRNA vaccination-elicited RBD-specific memory B cells reveals strong but incomplete immune escape of the SARS-CoV-2 Omicron variant.

The SARS-CoV-2 Omicron variant can escape neutralization by vaccine-elicited and convalescent antibodies. Memory B cells (MBCs) represent another layer of protection against SARS-CoV-2, as they persist after infection and vaccination and improve their affinity. Whether MBCs elicited by mRNA vaccines can recognize the Omicron variant remains unclear. We assessed the affinity and neutralization potency against the Omicron variant of several hundred naturally expressed MBC-derived monoclonal IgG antibodies from vaccinated COVID-19-recovered and -naive individuals. Compared with other variants of concern, Omicron evaded recognition by a larger proportion of MBC-derived antibodies, with only 30% retaining high affinity against the Omicron RBD, and the reduction in neutralization potency was even more pronounced. Nonetheless, neutralizing MBC clones could be found in all the analyzed individuals. Therefore, despite the strong immune escape potential of the Omicron variant, these results suggest that the MBC repertoire generated by mRNA vaccines still provides some protection against the Omicron variant in vaccinated individuals.

mRNA vaccination of naive and COVID-19-recovered individuals elicits potent memory B cells that recognize SARS-CoV-2 variants.

In addition to serum immunoglobulins, memory B cell (MBC) generation against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is another layer of immune protection, but the quality of MBC responses in naive and coronavirus disease 2019 (COVID-19)-recovered individuals after vaccination remains ill defined. We studied longitudinal cohorts of naive and disease-recovered individuals for up to 2 months after SARS-CoV-2 mRNA vaccination. We assessed the quality of the memory response by analysis of antibody repertoires, affinity, and neutralization against variants of concern (VOCs) using unbiased cultures of 2,452 MBCs. Upon boosting, the MBC pool of recovered individuals expanded selectively, matured further, and harbored potent neutralizers against VOCs. Although naive individuals had weaker neutralizing serum responses, half of their RBD-specific MBCs displayed high affinity toward multiple VOCs, including delta (B.1.617.2), and one-third retained neutralizing potency against beta (B.1.351). Our data suggest that an additional challenge in naive vaccinees could recall such affinity-matured MBCs and allow them to respond efficiently to VOCs.

Factors associated with the emergence of integrase resistance mutations in patients failing dual or triple integrase inhibitor-based regimens in a French national survey.

BACKGROUND: Successful 2-drug regimens (2DRs) for HIV were made possible by the availability of drugs combining potency and tolerability with a high genetic barrier to resistance. How these deal with resistance development/re-emergence, compared with 3DRs, is thus of paramount importance. MATERIALS AND METHODS: A national survey including patients who were either naive or experienced with any 2DR or 3DR but failing integrase strand transfer inhibitor (INSTI)-containing regimens [two consecutive plasma viral load (VL) values >50 copies/mL] was conducted between 2014 and 2019. Genotypic resistance tests were interpreted with the v28 ANRS algorithm. RESULTS: Overall, 1104 patients failing any INSTI-containing regimen (2DRs, n = 207; 3DRs, n = 897) were analysed. Five hundred and seventy-seven (52.3%) patients were infected with a B subtype and 527 (47.3%) with non-B subtypes. Overall, 644 (58%) patients showed no known integrase resistance mutations at failure. In multivariate analysis, factors associated with the emergence of at least one integrase mutation were: high VL at failure (OR = 1.24 per 1 log10 copies/mL increase); non-B versus B subtype (OR = 1.75); low genotypic sensitivity score (GSS) (OR = 0.10 for GSS = 2 versus GSS = 0-0.5); and dolutegravir versus raltegravir (OR = 0.46). Although 3DRs versus 2DRs reached statistical significance in univariate analysis (OR = 0.59, P = 0.007), the variable is not retained in the final model. CONCLUSIONS: This study is one of the largest studies characterizing integrase resistance in patients failing any INSTI-containing 2DR or 3DR in routine clinical care and reveals factors associated with emergence of integrase resistance that should be taken into consideration in clinical management. No difference was evidenced between patients receiving a 2DR or a 3DR.

Surveillance of HIV-1 primary infections in France from 2014 to 2016: toward stable resistance, but higher diversity, clustering and virulence?

OBJECTIVES: Patients with primary HIV-1 infection (PHI) are a particular population, giving important insight about ongoing evolution of transmitted drug resistance-associated mutation (TDRAM) prevalence, HIV diversity and clustering patterns. We describe these evolutions of PHI patients diagnosed in France from 2014 to 2016. METHODS: A total of 1121 PHI patients were included. TDRAMs were characterized using the 2009 Stanford list and the French ANRS algorithm. Viral subtypes and recent transmission clusters (RTCs) were also determined. RESULTS: Patients were mainly MSM (70%) living in the Paris area (42%). TDRAMs were identified among 10.8% of patients and rose to 18.6% when including etravirine and rilpivirine TDRAMs. Prevalences of PI-, NRTI-, first-generation NNRTI-, second-generation NNRTI- and integrase inhibitor-associated TDRAMs were 2.9%, 5.0%, 4.0%, 9.4% and 5.4%, respectively. In a multivariable analysis, age >40 years and non-R5 tropic viruses were associated with a >2-fold increased risk of TDRAMs. Regarding HIV diversity, subtype B and CRF02_AG (where CRF stands for circulating recombinant form) were the two main lineages (56% and 20%, respectively). CRF02_AG was associated with higher viral load than subtype B (5.83 versus 5.40 log10 copies/mL, P=0.004). We identified 138 RTCs ranging from 2 to 14 patients and including overall 41% from the global population. Patients in RTCs were younger, more frequently born in France and more frequently MSM. CONCLUSIONS: Since 2007, the proportion of TDRAMs has been stable among French PHI patients. Non-B lineages are increasing and may be associated with more virulent CRF02_AG strains. The presence of large RTCs highlights the need for real-time cluster identification to trigger specific prevention action to achieve better control of the epidemic.

Stable prevalence of transmitted drug resistance mutations and increased circulation of non-B subtypes in antiretroviral-naive chronically HIV-infected patients in 2015/2016 in France.

OBJECTIVES: We estimated the prevalence of transmitted-drug-resistance-associated mutations (TDRAMs) in antiretroviral-naive chronically HIV-1-infected patients. PATIENTS AND METHODS: TDRAMs were sought in samples from 660 diagnosed HIV-1-infected individuals in 2015/2016 in 33 HIV clinical centres. Weighted analyses, considering the number of patients followed in each centre, were used to derive representative estimates of the percentage of individuals with TDRAMs. Results were compared with those of the 2010/2011 survey (n = 661) using the same methodology. RESULTS: At inclusion, median CD4 cell counts and plasma HIV-1 RNA were 394 and 350/mm3 (P = 0.056) and 4.6 and 4.6 log10 copies/mL (P = 0.360) in the 2010/2011 survey and the 2015/2016 survey, respectively. The frequency of non-B subtypes increased from 42.9% in 2010/2011 to 54.8% in 2015/2016 (P < 0.001), including 23.4% and 30.6% of CRF02_AG (P = 0.004). The prevalence of virus with protease or reverse-transcriptase TDRAMs was 9.0% (95% CI = 6.8-11.2) in 2010/2011 and 10.8% (95% CI = 8.4-13.2) in 2015/2016 (P = 0.269). No significant increase was observed in integrase inhibitor TDRAMs (6.7% versus 9.2%, P = 0.146). Multivariable analysis showed that men infected with the B subtype were the group with the highest risk of being infected with a resistant virus compared with others (adjusted OR = 2.2, 95% CI = 1.3-3.9). CONCLUSIONS: In France in 2015/2016, the overall prevalence of TDRAMs was 10.8% and stable compared with 9.0% in the 2010/2011 survey. Non-B subtypes dramatically increased after 2010. Men infected with B subtype were the group with the highest risk of being infected with a resistant virus, highlighting the need to re-emphasize safe sex messages.

New HIV-1 circulating recombinant form 94: from phylogenetic detection of a large transmission cluster to prevention in the age of geosocial-networking apps in France, 2013 to 2017.

BackgroundEnding the HIV pandemic must involve new tools to rapidly identify and control local outbreaks and prevent the emergence of recombinant strains with epidemiological advantages.AimThis observational study aimed to investigate in France a cluster of HIV-1 cases related to a new circulating recombinant form (CRF). The confirmation this CRF's novelty as well as measures to control its spread are presented.MethodsPhylogenetic analyses of HIV sequences routinely generated for drug resistance genotyping before 2018 in French laboratories were employed to detect the transmission chain. The CRF involved was characterised by almost full-length viral sequencing for six cases. Cases' clinical data were reviewed. Where possible, epidemiological information was collected with a questionnaire.ResultsThe transmission cluster comprised 49 cases, mostly diagnosed in 2016-2017 (n = 37). All were infected with a new CRF, CRF94_cpx. The molecular proximity of this CRF to X4 strains and the high median viraemia, exceeding 5.0 log10 copies/mL, at diagnosis, even in chronic infection, raise concerns of enhanced virulence. Overall, 41 cases were diagnosed in the Ile-de-France region and 45 were men who have sex with men. Among 24 cases with available information, 20 reported finding partners through a geosocial networking app. Prevention activities in the area and population affected were undertaken.ConclusionWe advocate the systematic use of routinely generated HIV molecular data by a dedicated reactive network, to improve and accelerate targeted prevention interventions. Geosocial networking apps can play a role in the spread of outbreaks, but could also deliver local targeted preventive alerts.

Impact of Human Immunodeficiency Virus Type 1 Minority Variants on the Virus Response to a Rilpivirine-Based First-line Regimen.

Background: Minority resistant variants of human immunodeficiency virus type 1 (HIV-1) could influence the virological response to treatment based on nonnucleoside reverse transcriptase inhibitors (NNRTIs). Data on minority rilpivirine-resistant variants are scarce. This study used next-generation sequencing (NGS) to identify patients harboring minority resistant variants to nucleos(t)ide reverse transcriptase inhibitors and NNRTIs and to assess their influence on the virological response (VR). Methods: All the subjects, 541 HIV-1-infected patients started a first-line regimen containing rilpivirine. VR was defined as a HIV-1 RNA load <50 copies/mL at month 6 with continued suppression at month 12. NGS was performed at baseline (retrospectively) on the 454 GS-FLX platform (Roche). Results: NGS revealed resistance-associated mutations accounting for 1% to <5% of variants in 17.2% of samples, for 5%-20% in 5.7% of samples, and for >20% in 29% of samples. We identified 43 (8.8%) and 36 (7.4%) patients who harbored rilpivirine-resistant variants with a 1% sensitivity threshold according to the French National Agency for Research on AIDS and Viral Hepatitis and Stanford algorithms, respectively. The VR was 96.9% at month 12. Detection of minority rilpivirine resistant variants was not associated with virological failure (VF). Multivariate analysis indicated that VF at month 12 was associated with a CD4 count <250 cells/µL at baseline, a slower decrease in viral load at month 3, and rilpivirine resistance at baseline using the Stanford algorithm with a 20% threshold. Conclusions: Minority resistant variants had no impact on the VR of treatment-naive patients to a rilpivirine-based regimen.

Retreatment with sofosbuvir and simeprevir of patients with hepatitis C virus genotype 1 or 4 who previously failed a daclatasvir-containing regimen.

UNLABELLED: Failure to achieve sustained virological response (SVR) with hepatitis C virus (HCV) direct-acting antiviral-based regimens is commonly associated with emergence of resistance-associated variants (RAVs). To avoid cross-resistance, recent guidelines recommend that patients who have failed on nonstructural protein 5A (NS5A) inhibitors should be retreated with sofosbuvir (SOF; NS5B inhibitor) combined with simeprevir (SIM; protease inhibitor [PI]); however, supporting evidence is lacking. This "real-world" study comprised patients who had failed to achieve SVR on previous NS5A-based therapy with daclatasvir (DCV) plus pegylated interferon (Peg-IFN) and ribavirin (RBV), with (n = 3) or without (n = 13) asunaprevir (ASV; PI). All 16 patients were retreated for 12 weeks with SOF plus SIM, without RBV. Antiviral efficacy was evaluated using the primary endpoint of SVR12 (SVR 12 weeks post-treatment); on-treatment response was also assessed. Patients (N = 16; 13 male; mean age: 54 years [range, 43-73]) were chronically infected with HCV genotype (GT) 1 (1a, n = 11; 1b, n = 3) or 4 (n = 2); they had advanced fibrosis or compensated cirrhosis (FibroScan, 9.6-70 kPa; cirrhosis, n = 9); median baseline HCV-RNA level was 1.38 × 10(6) IU/mL. No patient discontinued treatment because of adverse events or virological failure. All patients achieved HCV RNA below lower limit of quantification (<12 IU/mL) by end of treatment (EOT) and 10 of 16 had a rapid response (week 4). SVR12 was achieved by 14 of 16 patients; the remaining 2 relapsed by 4 weeks post-EOT (both were GT 1a infected with cirrhosis; 1 had previously failed DCV-ASV plus Peg-IFN and RBV). Presence of SIM RAVs/polymorphisms (R155K and Q80K) at study baseline did not predict retreatment failure. CONCLUSION: Our findings support the concept of retreating NS5A inhibitor failures with SOF combined with SIM. However, the most difficult-to-cure patients may need more than 12 weeks of treatment and/or the addition of RBV. (Hepatology 2016;63:1809-1816).

Naturally Occurring Resistance-Associated Variants of Hepatitis C Virus Protease Inhibitors in Poor Responders to Pegylated Interferon-Ribavirin.

The pretherapeutic presence of protease inhibitor (PI) resistance-associated variants (RAVs) has not been shown to be predictive of triple-therapy outcomes in treatment-naive patients. However, they may influence the outcome in patients with less effective pegylated interferon (pegIFN)-ribavirin (RBV) backbones. Using hepatitis C virus (HCV) population sequence analysis, we retrospectively investigated the prevalence of baseline nonstructural 3 (NS3) RAVs in a multicenter cohort of poor IFN-RBV responders (i.e., prior null responders or patients with a viral load decrease of <1 log IU/ml during the pegIFN-RBV lead-in phase). The impact of the presence of these RAVs on the outcome of triple therapy was studied. Among 282 patients, the prevalances (95% confidence intervals) of baseline RAVs ranged from 5.7% (3.3% to 9.0%) to 22.0% (17.3% to 27.3%), depending to the algorithm used. Among mutations conferring a >3-fold shift in 50% inhibitory concentration (IC50) for telaprevir or boceprevir, T54S was the most frequently detected mutation (3.9%), followed by A156T, R155K (0.7%), V36M, and V55A (0.35%). Mutations were more frequently found in patients infected with genotype 1a (7.5 to 23.6%) than 1b (3.3 to 19.8%) (P = 0.03). No other sociodemographic or viroclinical characteristic was significantly associated with a higher prevalence of RAVs. No obvious effect of baseline RAVs on viral load was observed. In this cohort of poor responders to IFN-RBV, no link was found with a sustained virological response to triple therapy, regardless of the algorithm used for the detection of mutations. Based on a cross-study comparison, baseline RAVs are not more frequent in poor IFN-RBV responders than in treatment-naive patients and, even in these difficult-to-treat patients, this study demonstrates no impact on treatment outcome, arguing against resistance analysis prior to treatment.

Comparison of Dual Monoclonal Antibody Therapies for COVID-19 Evolution: A Multicentric Retrospective Study.

BACKGROUND: Neutralizing antibodies targeting the SARS-CoV-2 Spike protein reduce COVID-19-related risk of hospitalization, particularly in high-risk individuals. The COCOPREV-R study aimed to evaluate and compare clinical outcomes in high-risk SARS-CoV-2 patients treated with dual monoclonal antibody therapies and to identify associated virological factors. METHODS: The COCOPREV-R study retrospectively collected real-world data from high-risk patients receiving Bamlanivimab/Etesevimab or Casirivimab/Imdevimab dual monoclonal antibody therapies (22 February 2021 to 15 June 2021). RESULTS: The study included 1004 patients with COVID-19, of whom 691 received Bamlanivimab/Etesevimab and 313 received Casirivimab/Imdevimab. The alpha variant represented 90.1% of those for whom data were available. The risk of hospitalization within 30 days was lower with Bamlanivimab/Etesevimab (12.7%, CI 95% [9.9-16.3%]) compared to Casirivimab/Imdevimab (28.4%, CI 95% [22.7-35.1%) (p < 0.001). The 30-day mortality rates were comparable between both groups (p = 0.982). Analysis of SARS-CoV-2 PCR negativity showed no difference between the two treatment groups (95.2% [93.0-96.9%] and 93.5% [89.1-96.6%] until day 30, p = 0.851 for Bamlanivimab/Etesevimab and Casirivimab/Imdevimab, respectively). Among persistently positive samples with available sequencing results (n = 43), Spike protein changes occurred only in Bamlanivimab/Etesevimab (42.9%) vs. Casirivimab/Imdevimab (0.0%) groups. Q493R (25.0%) and E484K (12.5%) were the most common mutations selected by Bamlanivimab/Etesevimab in follow-up samples. Other factors (immunodepression, comorbidities, and age) did not appear to be associated with the occurrence of Spike protein mutations. CONCLUSIONS: A higher rate of hospitalization was seen with Casirivimab/Imdevimab (RONAPREVE®) in comparison with Bamlanivimab/Etesevimab treatment, but with the emergence of Spike mutations only in the Bamlanivimab/Etesevimab group.

The Cobas AmpliPrep/Cobas TaqMan HCV test, version 2.0, real-time PCR assay accurately quantifies hepatitis C virus genotype 4 RNA.

Accurate hepatitis C virus (HCV) RNA quantification is mandatory for the management of chronic hepatitis C therapy. The first-generation Cobas AmpliPrep/Cobas TaqMan HCV test (CAP/CTM HCV) underestimated HCV RNA levels by >1-log10 international units/ml in a number of patients infected with HCV genotype 4 and occasionally failed to detect it. The aim of this study was to evaluate the ability of the Cobas AmpliPrep/Cobas TaqMan HCV test, version 2.0 (CAP/CTM HCV v2.0), to accurately quantify HCV RNA in a large series of patients infected with different subtypes of HCV genotype 4. Group A comprised 122 patients with chronic HCV genotype 4 infection, and group B comprised 4 patients with HCV genotype 4 in whom HCV RNA was undetectable using the CAP/CTM HCV. Each specimen was tested with the third-generation branched DNA (bDNA) assay, CAP/CTM HCV, and CAP/CTM HCV v2.0. The HCV RNA level was lower in CAP/CTM HCV than in bDNA in 76.2% of cases, regardless of the HCV genotype 4 subtype. In contrast, the correlation between bDNA and CAP/CTM HCV v2.0 values was excellent. CAP/CTM HCV v2.0 accurately quantified HCV RNA levels in the presence of an A-to-T substitution at position 165 alone or combined with a G-to-A substitution at position 145 of the 5' untranslated region of HCV genome. In conclusion, CAP/CTM HCV v2.0 accurately quantifies HCV RNA in genotype 4 clinical specimens, regardless of the subtype, and can be confidently used in clinical trials and clinical practice with this genotype.

Human type I IFN deficiency does not impair B cell response to SARS-CoV-2 mRNA vaccination.

Inborn and acquired deficits of type I interferon (IFN) immunity predispose to life-threatening COVID-19 pneumonia. We longitudinally profiled the B cell response to mRNA vaccination in SARS-CoV-2 naive patients with inherited TLR7, IRF7, or IFNAR1 deficiency, as well as young patients with autoantibodies neutralizing type I IFNs due to autoimmune polyendocrine syndrome type-1 (APS-1) and older individuals with age-associated autoantibodies to type I IFNs. The receptor-binding domain spike protein (RBD)-specific memory B cell response in all patients was quantitatively and qualitatively similar to healthy donors. Sustained germinal center responses led to accumulation of somatic hypermutations in immunoglobulin heavy chain genes. The amplitude and duration of, and viral neutralization by, RBD-specific IgG serological response were also largely unaffected by TLR7, IRF7, or IFNAR1 deficiencies up to 7 mo after vaccination in all patients. These results suggest that induction of type I IFN is not required for efficient generation of a humoral response against SARS-CoV-2 by mRNA vaccines.

High-dose pegylated interferon-α and ribavirin in nonresponder hepatitis C patients and relationship with IL-28B genotype (SYREN trial).

BACKGROUND & AIMS: In patients with chronic hepatitis C who failed to respond to standard therapy, high-dose pegylated interferon (IFN)-α and/or ribavirin could induce a stronger antiviral response and prevent treatment failure and HCV resistance when combined with direct-acting antivirals. The influence of genetic determinants in this context remains unknown. METHODS: Eighty-three patients infected with HCV genotype 1 who were nonresponsive to standard therapy received pegylated IFN-α2a (360 µg once per week or 180 µg twice per week) with ribavirin (1.0-1.2 or 1.2-1.6 g/d) for up to 72 weeks. Virological responses were assessed at different time points, and the influence of the IL-28B genotype was studied. RESULTS: At weeks 12 and 24, respectively, 47 (56.6%) and 50 (60.2%) patients achieved a ≥2-Log10 decrease of HCV RNA levels; 8 (9.6%) and 21 (25.3%) patients had undetectable HCV RNA after 12 and 24 weeks of treatment, respectively. Patients with a CT IL-28B genotype responded significantly better and earlier than those with a TT genotype. In multivariate analysis, the IL-28B genotype was an independent predictor of the virological responses at weeks 4, 12, and 24. CONCLUSIONS: High-dose pegylated IFN-α with standard or high doses of ribavirin induces a potent antiviral response in a substantial number of patients who did not respond to standard therapy. The IL-28B genotype is an independent predictor of the antiviral response. High-dose pegylated IFN-α in combination with ribavirin and protease inhibitors appears as an attractive option for future study in this population.

Erythrocyte and plasma ribavirin concentrations in the assessment of early and sustained virological responses to pegylated interferon-alpha 2a and ribavirin in patients coinfected with hepatitis C virus and HIV.

OBJECTIVES: To determine the relationship between erythrocyte and plasma ribavirin concentrations in hepatitis C virus (HCV)/HIV-coinfected patients, and to correlate ribavirin exposure with early and sustained virological response (EVR and SVR) and haemoglobin level reductions. METHODS: Clinical and biological data from 68 HCV/HIV-coinfected patients were recorded at baseline, week 4 (W4), week 12 and at 24 weeks after completion of treatment. Plasma and erythrocyte ribavirin concentrations were determined 12 h after the final ribavirin dose (C(min)). RESULTS: Erythrocyte ribavirin concentrations were 100-fold higher than plasma concentrations, with a significant relationship between them (P < 0.05). In patients with HCV genotype 1 or 4, a plasma ribavirin C(min) threshold of 1.95 mg/L at W4 tended to predict EVR [sensitivity 44%; specificity 87%; AUC 0.67 (95% CI 0.50-0.84)] and was predictive of SVR [sensitivity 58%; specificity 84%; AUC 0.71 (95% CI 0.51-0.90)]. Among patients with these HCV genotypes, an erythrocyte ribavirin C(min) threshold of 146 mg/L at W4 was found to be the best value for discriminating between responders and non-responders for both EVR [sensitivity 67%; specificity 75%; AUC 0.58 (95% CI 0.24-0.93)] and SVR [sensitivity 50%; specificity 80%; AUC 0.70 (95% CI 0.39-1.01)]. We also demonstrated a significant relationship between reduced haemoglobin levels and plasma ribavirin C(min) at W4 (P = 0.05). CONCLUSIONS: Therapeutic drug monitoring may be useful for the management of anti-HCV treatment in HCV/HIV-coinfected patients.

Performance of a high-throughput, automated enzyme immunoassay for the detection of SARS-CoV-2 antigen, including in viral "variants of concern": Implications for clinical use.

Direct detection of SARS-CoV-2 viral antigens could replace RT-PCR, provided that its clinical performance is validated in different epidemiological settings. Here, we evaluated the performance of the VITROS Antigen test, an enzyme immunoassay detecting a SARS-CoV-2 antigen, in NPSs from 3 cohorts of patients. METHODS: Three cohorts including SARS-CoV-2 RNA-positive samples collected during the first and second wave of the French epidemic between March 2020 and February 2021 (including variant B.1.1.7/α and variant B.1.351/ß). RESULTS: Among the 1763 prospectively tested subjects, 8.2% (145/1763) were SARS-CoV-2 RNA-positive by RT-PCR. Using Ct ≤ 30 and Ct ≤ 35 as thresholds, the sensitivities of the antigen assay were 98.8% (93.6-100%) and 93.5% (87.0-97.3%), respectively. The overall specificity of the assay was 100% (1614/1614; 99.8-100%). In a retrospective cohort of subjects infected with variants of concern, 90.4% (47/52) of NPSs containing B. B.1.1.7/α (Ct ≤ 35) and 100% (7/7) of those containing B.1.351/ß were positive with the VITROS EIA SARS-CoV-2 Antigen test. CONCLUSION: The excellent performance of the EIA Antigen test reported here, including in patients infected with viral "variants of concern", support the use of high-throughput, EIA-based SARS-CoV-2 antigen assays as an alternative or complement to nucleic acid testing in order to scale-up laboratory screening and diagnostic capacities.

Performance of 22 Rapid Lateral Flow Tests for SARS-CoV-2 Antigen Detection and Influence of "Variants of Concern": Implications for Clinical Use.

Large-scale head-to-head assessment of the performance of lateral-flow tests (LFTs) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen is required in the context of the continuous emergence of new viral variants. The aim of this study was to evaluate the performance of 22 rapid LFTs for the detection of SARS-CoV-2 antigens. The clinical performance of 22 LFTs was evaluated in 1,157 samples collected in the Greater Paris area. The 8 best-performing LFTs were further assessed for their ability to detect 4 variants of concern (VOC), including the alpha, beta, delta, and omicron (BA.1) variants. The specificity of SARS-CoV-2 LFTs was generally high (100% for 15 of them) but was insufficient (<75%) for 3 tests. Sensitivity of the LFTs varied from 30.0% to 79.7% compared to nucleic acid amplification testing (NAAT). Using a cycle threshold (CT) cutoff of ≤25, sensitivity of the assays ranged from 59.7% to 100%. The 8 best-performing assays had a sensitivity of ≥80% for the detection of the 4 VOC when the CT was ≤25. Falsely negative SARS-CoV-2 antigen LFT results were observed with omicron, due to the occurrence of low viral loads (CT > 30 in 32% of samples) during the two first days following symptom onset. Several LFTs exhibited satisfactory sensitivity and specificity, whereas a few others yielded an unacceptable proportion of false-positive results and/or lacked sensitivity. The sensitivity of the best-performing assays was not influenced by VOC, including alpha, beta, delta, and omicron variants. The ability of LFTs to detect the omicron variant could be reduced during the first days following symptom onset due to lower viral loads than with other variants. IMPORTANCE The use of lateral-flow tests (LFTs) to detect SARS-CoV-2 has expanded worldwide. LFTs detect SARS-CoV-2 viral antigen and are less sensitive than nucleic acid amplification testing (NAAT). Their performance must be evaluated independently of the manufacturers. Our study assessed the performance of 22 SARS-CoV-2 antigen LFTs in large panels of well-characterized samples. The majority of LFTs tested exhibited satisfactory sensitivity and specificity, while some assays yielded unacceptable proportions of false-positive results, and others lacked sensitivity for samples containing large amounts of virus. The sensitivity of the best-performing assays did not vary according to the VOC, including the alpha, beta, delta, and omicron variants.

Interpretation of real-time PCR results for hepatitis C virus RNA when viral load is below quantification limits.

Hepatitis C virus RNA quantification results obtained in 18 laboratories using real-time PCR methods with 10 negative samples and 22 sample dilutions (viral loads of 0.5 to 500 IU/ml) showed a score of correct results of up to 93.5%. However, 55.6% of the laboratories did not follow the recommendations for the interpretation of their results, leading to ambiguous conclusions.

Diagnosis and Monitoring of Hepatitis B Virus Infection Using the Cobas® HBV Test for Use on the Cobas® 4800 System.

(1) Background: Sensitive and accurate nucleic acid amplification technologies are now recommended for hepatitis B virus (HBV) DNA detection and quantification in clinical practice to diagnose and monitor hepatitis B infection. The aim of this study was to assess the analytical and clinical performance of the cobas® HBV Test on the cobas® 4800 System. (2) Methods: Standard panel and clinical specimens were tested in parallel with three different real-time commercial PCR assays including the cobas ® HBV Test, the Cobas® AmpliPrep/Cobas® TaqMan HBV Test v2.0 and Alinity™ m HBV assay. (3) Results: The specificity of the cobas® HBV Test was 97.9%. The limit of detection was estimated to be 2.1 IU/mL. Intra-assay and interassay coefficients of variation varied from 0.14% to 1.92% and 2.16% to 12.02%, respectively. HBV DNA levels in patients infected with different HBV genotypes strongly correlated with those measured by the two other commercial comparators assays. (4) Conclusions: The cobas® HBV Test can be confidently used to detect and accurately quantify HBV DNA in clinical practice as well as in clinical trials with the new anti-HBV drugs currently in development.