With the availability of widespread SARS-CoV-2 vaccination, high-throughput quantitative anti-spike protein serological testing will likely become increasingly important. Here, we investigated the ...performance characteristics of the recently FDA-authorized semiquantitative anti-spike protein AdviseDx SARS-CoV-2 IgG II assay compared to the FDA-authorized anti-nucleocapsid protein Abbott Architect SARS-CoV-2 IgG, Roche Elecsys anti-SARS-CoV-2-S, EuroImmun anti-SARS-CoV-2 enzyme-linked immunosorbent assay (ELISA), and GenScript surrogate virus neutralization assays and examined the humoral response associated with vaccination, natural protection, and vaccine breakthrough infection. The AdviseDx assay had a clinical sensitivity at 14 days after symptom onset or 10 days after PCR detection of 95.6% (65/68; 95% confidence interval CI, 87.8 to 98.8%), with two discrepant individuals seroconverting shortly thereafter. The AdviseDx assay demonstrated 100% positive percent agreement with the four other assays examined using the same symptom onset or PCR detection cutoffs. Using a recently available WHO international standard for anti-SARS-CoV-2 antibody, we provide assay unit conversion factors to international units for each of the assays examined. We performed a longitudinal survey of healthy vaccinated individuals, finding that median AdviseDx immunoglobulin levels peaked 7 weeks after first vaccine dose at approximately 4,000 IU/ml. Intriguingly, among the five assays examined, there was no significant difference in antigen binding level or neutralizing activity between two seropositive patients protected against SARS-CoV-2 infection in a previously described fishing vessel outbreak and five health care workers who experienced vaccine breakthrough of SARS-CoV-2 infection, all with variants of concern. These findings suggest that protection against SARS-CoV-2 infection cannot currently be predicted exclusively using
antibody assays against wild-type SARS-CoV-2 spike. Further work is required to establish protective correlates for SARS-CoV-2 infection.
There are many emerging and re-emerging globally prevalent viruses for which there are no licensed vaccines or antiviral medicines. Arbidol (ARB, umifenovir), used clinically for decades in several ...countries as an anti-influenza virus drug, inhibits many other viruses. In the current study, we show that ARB inhibits six different isolates of Zika virus (ZIKV), including African and Asian lineage viruses in multiple cell lines and primary human vaginal and cervical epithelial cells. ARB protects against ZIKV-induced cytopathic effects. Time of addition studies indicate that ARB is most effective at suppressing ZIKV when added to cells prior to infection. Moreover, ARB inhibits pseudoviruses expressing the ZIKV Envelope glycoprotein. Thus, ARB, a broadly acting anti-viral agent with a well-established safety profile, inhibits ZIKV, likely by blocking viral entry.
The cellular processes that support human coronavirus replication and contribute to the pathogenesis of severe disease remain incompletely understood. Many viruses, including coronaviruses, cause ...endoplasmic reticulum (ER) stress during infection. IRE1α is a component of the cellular response to ER stress that initiates non-conventional splicing of
mRNA. Spliced
encodes a transcription factor that induces the expression of ER-related targets. Activation of the IRE1α-XBP1 pathway occurs in association with risk factors for severe human coronavirus infection. In this study, we found that the human coronaviruses HCoV-OC43 (human coronavirus OC43) and SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2) both robustly activate the IRE1α-XBP1 branch of the unfolded protein response in cultured cells. Using IRE1α nuclease inhibitors and genetic knockdown of IRE1α and XBP1, we found that these host factors are required for optimal replication of both viruses. Our data suggest that IRE1α supports infection downstream of initial viral attachment and entry. In addition, we found that ER stress-inducing conditions are sufficient to enhance human coronavirus replication. Furthermore, we found markedly increased XBP1 in circulation in human patients with severe coronavirus disease 2019 (COVID-19). Together, these results demonstrate the importance of IRE1α and XBP1 for human coronavirus infection.IMPORTANCEThere is a critical need to understand the cellular processes co-opted during human coronavirus replication, with an emphasis on identifying mechanisms underlying severe disease and potential therapeutic targets. Here, we demonstrate that the host proteins IRE1α and XBP1 are required for robust infection by the human coronaviruses, SARS-CoV-2 and HCoV-OC43. IRE1α and XBP1 participate in the cellular response to ER stress and are activated during conditions that predispose to severe COVID-19. We found enhanced viral replication with exogenous IRE1α activation, and evidence that this pathway is activated in humans during severe COVID-19. Together, these results demonstrate the importance of IRE1α and XBP1 for human coronavirus infection.
Most quantitative anti-rubella IgG immunoassays have been calibrated to an international standard with a suggested cutoff for inference of protective immunity at 10 IU/mL.1 However, variable results ...for specimens tested with different assays have been reported,2,3 although the extent to which imprecision and laboratory-specific practices contribute to the suggested poor interassay agreement is unclear We assessed the current state of interassay and interlaboratory antirubella immunoassay performance by leveraging anti-rubella IgG results from proficiency testing (PT) Diagnostic Immunology S surveys conducted by the College of American Pathologists. For most manufacturers, anti-rubella IgG values were below 10 IU/mL. ...the consistently high Roche and Siemens results observed in strongly positive samples (Figure, A) were recapitulated in a PT sample with a consensus-defined value near the decision limit. ...prior reports have suggested that Siemens and Roche platforms may also yield the highest values for patient specimens.4,5 Anti-rubella IgG values influence clinical management, and discordance between assays could significantly impact patient care, including unnecessary immunization of those with preexisting immunity or failure to immunize those at risk.
Abstract
Background
The Recipient Epidemiology and Donor Evaluation Study-IV-Pediatric (REDS-IV-P) Epidemiology, Surveillance and Preparedness of the Novel SARS-CoV-2 Epidemic (RESPONSE) ...seroprevalence study conducted monthly cross-sectional testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in blood donors in 6 US metropolitan regions to estimate the extent of SARS-CoV-2 infections over time.
Methods
During March–August 2020, approximately ≥1000 serum specimens were collected monthly from each region and tested for SARS-CoV-2 antibodies using a well-validated algorithm. Regional seroprevalence estimates were weighted based on demographic differences compared with the general population. Seroprevalence was compared with reported coronavirus disease 2019 (COVID-19) case rates over time.
Results
For all regions, seroprevalence was <1.0% in March 2020. New York, New York, experienced the biggest increase (peak seroprevalence, 15.8% in May). All other regions experienced modest increases in seroprevalence (1%–2% in May–June to 2%–4% in July–August). Seroprevalence was higher in younger, non-Hispanic black, and Hispanic donors. Temporal increases in donor seroprevalence correlated with reported case rates in each region. In August, 1.3–5.6 estimated cumulative infections (based on seroprevalence data) per COVID-19 case were reported to the Centers for Disease Control and Prevention.
Conclusions
Increases in seroprevalence were found in all regions, with the largest increase in New York. Seroprevalence was higher in non-Hispanic black and Hispanic than in non-Hispanic white blood donors. SARS-CoV-2 antibody testing of blood donor samples can be used to estimate the seroprevalence in the general population by region and demographic group. The methods derived from the RESPONSE seroprevalence study served as the basis for expanding SARS-CoV-2 seroprevalence surveillance to all 50 states and Puerto Rico.
SARS-CoV-2 serosurveillance of blood donors in 6 US regions enabled population weighted seroprevalence estimates. Seroprevelance rates were higher in younger, non-Hispanic Black, and Hispanic donors and correlated with regional case rates. The study has expanded to a national serosurveillance program.
A 58-year-old woman had congenital absence of vitamin D–binding protein, normocalcemia, mild disruption of bone metabolism, and severe autoimmune disease. A homozygous deletion of the group-specific ...component (
GC
) gene that encodes the protein was found, which provided new data about vitamin D metabolism.
Abstract
Objectives
To evaluate the real-world performance and reference intervals of the Binding Site Freelite serum free light chain (SFLC) assay (Thermo Fisher Scientific), a global standard for ...diagnosis, prognostication, and response assessment for monoclonal gammopathies.
Methods
An informatics-based approach was used to retrospectively evaluate concordance between SFLC and the orthogonal Sebia HYDRASYS immunofixation assay results in a large clinical data set consecutively reported between 2010 and 2020.
Results
Among patients with monoclonal-negative results by both SFLC and Sebia HYDRASYS immunofixation assays, 25% (1226/5057) had κ/λ ratios (KLRs) outside the manufacturer-defined and International Myeloma Working Group–cited normal reference interval of 0.26 to 1.65. These results were consistent over the study period and were not affected by sex, age, impaired kidney function, or assay antisera lot variation. Assay drift, in addition to other potential factors, affected the KLR distribution. Using International Statistical Classification of Diseases (ICD) codes, kidney function data, and the central 95% of KLR values generated on the Optilite platform (Thermo Fisher Scientific), we derived a new reference interval of 0.67 to 2.13, reducing the KLR false-positive rate to 8%. However, normal KLR persisted among 16% (14/85) of samples with free λ chains by immunofixation, warranting caution during interpretation.
Conclusions
Our analysis indicated that revision of Freelite SFLC reference intervals improves assay interpretation and should prompt reconsideration of Freelite reference intervals worldwide.
To the Editor.-The presence of antibodies to nuclear antigens (ANAs) above a threshold titer is a defining criterion for classification of systemic lupus erythematosus (SLE) and participation in ...clinical trials, and the probability of diagnosis of many autoimmune rheumatic diseases varies with the ANA titer.1,2 Consistent ANA titer results are therefore necessary for clinical and research purposes. Indirect fluorescent antibody (IFA) assays using HEp-2 cell substrates are widely considered the reference method for ANA detection. ...we sought to determine whether the manufacturer bias that we observed in proficiency testing specimens is consistent in clinical specimens.
Abstract
Background
Previous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and coronavirus disease 2019 (COVID-19) vaccination, independently and combined (“hybrid ...immunity”), result in partial protection from subsequent infection and strong protection from severe disease. Proportions of the US population who have been infected, vaccinated, or have hybrid immunity remain unclear, posing a challenge for assessing effective pandemic mitigation strategies.
Methods
In this serial cross-sectional study, nationwide blood donor specimens collected during January–December 2021 were tested for anti-spike and anti-nucleocapsid antibodies, and donor COVID-19 vaccination history of ≥1 dose was collected. Monthly seroprevalence induced from SARS-CoV-2 infection, COVID-19 vaccination, or both, were estimated. Estimates were weighted to account for demographic differences from the general population and were compared temporally and by demographic factors.
Results
Overall, 1 123 855 blood samples were assayed. From January to December 2021, the weighted percentage of donations with seropositivity changed as follows: seropositivity due to vaccination without previous infection, increase from 3.5% (95% confidence interval, 3.4%–3.7%) to 64.0%, (63.5%–64.5%); seropositivity due to previous infection without vaccination, decrease from 15.6% (15.2%–16.0%) to 11.7% (11.4%–12.0%); and seropositivity due to hybrid immunity, increase from 0.7% (0.6%–0.7%) to 18.9% (18.5%–19.3%). Combined seroprevalence from infection, vaccination, or both increased from 19.8% (19.3%–20.2%) to 94.5% (93.5%–94.0%). Infection- and vaccination-induced antibody responses varied significantly by age, race-ethnicity, and region, but not by sex.
Conclusions
Our results indicate substantial increases in population humoral immunity from SARS-CoV-2 infection, COVID-19 vaccination, and hybrid immunity during 2021. These findings are important to consider in future COVID-19 studies and long-term pandemic mitigation efforts.
During January–December 2021, among 1 123 855 blood donations, monthly population-weighted seroprevalence estimates due to coronavirus disease 2019 vaccination increased from 3.5% to 64.0%, previous severe acute respiratory syndrome coronavirus 2 infection decreased from 15.6% to 11.7%, and both previous infection and vaccination increased from 0.7% to 18.9%.
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