Rapid SARS-CoV-2 inactivation by mercury and LED UV-C lamps on different surfaces.

SARS-CoV-2 remains infectious for several hours on surfaces. It can be inactivated by UV-C irradiation but optimal conditions for rapid inactivation, especially on non-plastic surfaces remains unclear. A SARS-CoV-2 inoculum was irradiated with a UV-C LED (265 nm) or a UV-C mercury lamp (254 nm). Infectivity titers (TCID50/mL) and inactivation rates were then quantified on plastic, steel, tissue, paper and cardboard surfaces. We demonstrated that efficient SARS-CoV-2 inactivation (> 99.999% on plastic and steel, ≥ 99.8% on tissue, paper and cardboard) can be achieved by both a UV-C mercury lamp and a UV-C LED after 30 s of irradiations at 3 cm, corresponding to UV-C doses of 92.85 and 44.7 mJ/cm2, respectively. Inactivation on a plastic surface was more efficient with the mercury UV-C lamp (p < 0.005). The mercury UV-C lamp could be more relevant than the LED in high-risk settings, such as medical care or research laboratories.

Specific changes of erythroid regulators and hepcidin in patients infected by SARS-COV-2.

Iron metabolism is tightly linked to infectious and inflammatory signals through hepcidin synthesis. To date, iron homeostasis during SARS-CoV-2 infection has not yet been described. The aim of this study is to characterize the hepcidin and erythroid regulators (growth differentiation factor 15 (GDF-15) and erythroferrone (ERFE)) by measuring concentrations in plasma in context of COVID-19 disease.We performed a single-center observational study of patients with COVID-19 to evaluate concentrations of main regulatory proteins involved in iron homeostasis, namely: hepcidin, ERFE and GDF-15. SARS-CoV-2 infection (COVID-19+) was defined by a positive RT-PCR. Sixteen patients with COVID-19+ were gender-matched and age-matched to 16 patients with a sepsis unrelated to SARS-CoV-2 (COVID-19-) and were compared with non-parametric statistic test.Clinical and hematological parameters, plasma iron, transferrin, transferrin saturation, ferritin, soluble transferrin receptor and C reactive protein were not statistically different between both groups. Median plasma hepcidin concentrations were higher in the COVID-19+ group (44.1 (IQR 16.55-70.48) vs 14.2 (IQR 5.95-18.98) nmol/L, p=0.003), while median ERFE and GDF-15 concentrations were lower in the COVID-19+ group (0.16 (IQR 0.01-0.73) vs 0.89 (IQR 0.19-3.82) ng/mL, p=0.035; 2003 (IQR 1355-2447) vs 4713 (IQR 2082-7774) pg/mL, p=0015), respectively) compared with the COVID-19- group.This is the first study reporting lower ERFE and GDF-15 median concentrations in patients with COVID-19+ compared with patients with COVID-19-, associated with an increased median concentration of hepcidin in the COVID-19+ group compared with COVID19- group.

ELISA-Based Analysis Reveals an Anti-SARS-CoV-2 Protein Immune Response Profile Associated with Disease Severity.

Since the start of the COVID-19 pandemic, many studies have investigated the humoral response to SARS-CoV-2 during infection. Studies with native viral proteins constitute a first-line approach to assessing the overall immune response, but small peptides are an accurate and valuable tool for the fine characterization of B-cell epitopes, despite the restriction of this approach to the determination of linear epitopes. In this study, we used ELISA and peptides covering a selection of structural and non-structural SARS-CoV-2 proteins to identify key epitopes eliciting a strong immune response that could serve as a biological signature of disease characteristics, such as severity, in particular. We used 213 plasma samples from a cohort of patients well-characterized clinically and biologically and followed for COVID-19 infection. We found that patients developing severe disease had higher titers of antibodies mapping to multiple specific epitopes than patients with mild to moderate disease. These data are potentially important as they could be used for immunological profiling to improve our knowledge of the quantitative and qualitative characteristics of the humoral response in relation to patient outcome.

Antibody Responses after a Third Dose of COVID-19 Vaccine in Kidney Transplant Recipients and Patients Treated for Chronic Lymphocytic Leukemia.

The impact of a third dose of COVID-19 vaccine on antibody responses is unclear in immunocompromised patients. The objective of this retrospective study was to characterize antibody responses induced by a third dose of mRNA COVID-19 vaccine in 160 kidney transplant recipients and 20 patients treated for chronic lymphocytic leukemia (CLL). Prevalence of anti-spike IgG ≥ 7.1 and ≥ 30 BAU/mL after the third dose were 47% (75/160) and 39% (63/160) in kidney transplant recipients, and 57% (29/51) and 50% (10/20) in patients treated for CLL. Longitudinal follow-up identified a moderate increase in SARS-CoV-2 anti-spike IgG levels after a third dose of vaccine in kidney transplant recipients (0.19 vs. 5.28 BAU/mL, p = 0.03) and in patients treated for CLL (0.63 vs. 10.7 BAU/mL, p = 0.0002). This increase in IgG levels had a limited impact on prevalence of anti-spike IgG ≥ 30 BAU/mL in kidney transplant recipients (17%, 2/12 vs. 33%, 4/12, p = 0.64) and in patients treated for CLL (5%, 1/20 vs. 45%, 9/20, p = 0.008). These results highlight the need for vaccination of the general population and the importance of non-medical preventive measures to protect immunocompromised patients.

Humoral immunity to SARS-CoV-2 and seasonal coronaviruses in children and adults in north-eastern France.

BACKGROUND: Children are underrepresented in the COVID-19 pandemic and often experience milder disease than adolescents and adults. Reduced severity is possibly due to recent and more frequent seasonal human coronaviruses (HCoV) infections. We assessed the seroprevalence of SARS-CoV-2 and seasonal HCoV specific antibodies in a large cohort in north-eastern France. METHODS: In this cross-sectional seroprevalence study, serum samples were collected from children and adults requiring hospital admission for non-COVID-19 between February and August 2020. Antibody responses to SARS-CoV-2 and seasonal HCoV (229E, HKU1, NL63, OC43) were assessed using a bead-based multiplex assay, Luciferase-Linked ImmunoSorbent Assay, and a pseudotype neutralisation assay. FINDINGS: In 2,408 individuals, seroprevalence of SARS-CoV-2-specific antibodies was 7-8% with three different immunoassays. Antibody levels to seasonal HCoV increased substantially up to the age of 10. Antibody responses in SARS-CoV-2 seropositive individuals were lowest in adults 18-30 years. In SARS-CoV-2 seronegative individuals, we observed cross-reactivity between antibodies to the four HCoV and SARS-CoV-2 Spike. In contrast to other antibodies to SARS-CoV-2, specific antibodies to sub-unit 2 of Spike (S2) in seronegative samples were highest in children. Upon infection with SARS-CoV-2, antibody levels to Spike of betacoronavirus OC43 increased across the whole age spectrum. No SARS-CoV-2 seropositive individuals with low levels of antibodies to seasonal HCoV were observed. INTERPRETATION: Our findings underline significant cross-reactivity between antibodies to SARS-CoV-2 and seasonal HCoV, but provide no significant evidence for cross-protective immunity to SARS-CoV-2 infection due to a recent seasonal HCoV infection. In particular, across all age groups we did not observe SARS-CoV-2 infected individuals with low levels of antibodies to seasonal HCoV. FUNDING: This work was supported by the « URGENCE COVID-19 ¼ fundraising campaign of Institut Pasteur, by the French Government's Investissement d'Avenir program, Laboratoire d'Excellence Integrative Biology of Emerging Infectious Diseases (Grant No. ANR-10-LABX-62-IBEID), and by the REACTing (Research & Action Emerging Infectious Diseases), and by the RECOVER project funded by the European Union's Horizon 2020 research and innovation programme under grant agreement No. 101003589, and by a grant from LabEx IBEID (ANR-10-LABX-62-IBEID).

Synthesis and Antiviral Evaluation of (1,4-Disubstituted-1,2,3-Triazol)-(E)-2-Methyl-but-2-Enyl Nucleoside Phosphonate Prodrugs.

A series of hitherto unknown (1,4-disubstituted-1,2,3-triazol)-(E)-2-methyl-but-2-enyl nucleosides phosphonate prodrugs bearing 4-substituted-1,2,3-triazoles were prepared in a straight approach through an olefin acyclic cross metathesis as the key synthetic step. All novel compounds were evaluated for their antiviral activities against HBV, HIV and SARS-CoV-2. Among these molecules, only compound 15j, a hexadecyloxypropyl (HDP)/(isopropyloxycarbonyl-oxymethyl)-ester (POC) prodrug, showed activity against HBV in Huh7 cell cultures with 62% inhibition at 10 µM, without significant cytotoxicity (IC50 = 66.4 µM in HepG2 cells, IC50 = 43.1 µM in HepG2 cells) at 10 µM.

Modeling SARS-CoV-2 viral kinetics and association with mortality in hospitalized patients from the French COVID cohort.

The characterization of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral kinetics in hospitalized patients and its association with mortality is unknown. We analyzed death and nasopharyngeal viral kinetics in 655 hospitalized patients from the prospective French COVID cohort. The model predicted a median peak viral load that coincided with symptom onset. Patients with age ≥65 y had a smaller loss rate of infected cells, leading to a delayed median time to viral clearance occurring 16 d after symptom onset as compared to 13 d in younger patients (P < 10-4). In multivariate analysis, the risk factors associated with mortality were age ≥65 y, male gender, and presence of chronic pulmonary disease (hazard ratio [HR] > 2.0). Using a joint model, viral dynamics after hospital admission was an independent predictor of mortality (HR = 1.31, P < 10-3). Finally, we used our model to simulate the effects of effective pharmacological interventions on time to viral clearance and mortality. A treatment able to reduce viral production by 90% upon hospital admission would shorten the time to viral clearance by 2.0 and 2.9 d in patients of age <65 y and ≥65 y, respectively. Assuming that the association between viral dynamics and mortality would remain similar to that observed in our population, this could translate into a reduction of mortality from 19 to 14% in patients of age ≥65 y with risk factors. Our results show that viral dynamics is associated with mortality in hospitalized patients. Strategies aiming to reduce viral load could have an effect on mortality rate in this population.

Two-step strategy for the identification of SARS-CoV-2 variant of concern 202012/01 and other variants with spike deletion H69-V70, France, August to December 2020.

We report the strategy leading to the first detection of variant of concern 202012/01 (VOC) in France (21 December 2020). First, the spike (S) deletion H69-V70 (ΔH69/ΔV70), identified in certain SARS-CoV-2 variants including VOC, is screened for. This deletion is associated with a S-gene target failure (SGTF) in the three-target RT-PCR assay (TaqPath kit). Subsequently, SGTF samples are whole genome sequenced. This approach revealed mutations co-occurring with ΔH69/ΔV70 including S:N501Y in the VOC.

Clinical performance of four immunoassays for antibodies to SARS-CoV-2, including a prospective analysis for the diagnosis of COVID-19 in a real-life routine care setting.

OBJECTIVES: The aim of the present study was to evaluate the clinical performance of four SARS-CoV-2 immunoassays and their contribution in routine care for the diagnosis of COVID-19, in order to benefit of robust data before their extensive use. METHODS: The clinical performance of Euroimmun ELISA SARS-CoV-2 IgG, Abbott SARS-CoV-2 IgG, Wantai SARS-CoV-2 Ab ELISA, and DiaPro COVID-19 IgG confirmation were evaluated in the context of both a retrospective and a prospective analysis of COVID-19 patients. The retrospective analysis included plasma samples from 63 COVID-19 patients and 89 control (pre-pandemic) patients. The prospective study included 203 patients who tested either negative (n = 181) or positive (n = 22) by RT-PCR before serology sampling. RESULTS: The specificity was 92.1 %, 98.9 %, 100 % and 98.9 % and the sensitivity 14 days after onset of symptoms was 95.6 %, 95.6 %, 97.8 % and 95.6 % for Euroimmun IgG, Abbott IgG, Wantai Ab, and DiaPro IgG confirmation SARS-CoV-2 immunoassays, respectively. The low specificity of Euroimmun IgG (for ratio <5) was not confirmed in routine care setting (98.5 % negative agreement). Serology was complementary to RT-PCR in routine care and lead to identification of false positive (Ct>38, <2 targets detected) and false negative RT-PCR results (>1 month post onset of symptoms). CONCLUSIONS: Serology was complementary to RT-PCR for the diagnosis of COVID-19 at least 14 days after onset of symptoms. First line serology testing can be performed with Wantai Ab or Abbott IgG assays, while DiaPro IgG confirmation assay can be used as an efficient confirmation assay.