Homogeneous surrogate virus neutralization assay to rapidly assess neutralization activity of anti-SARS-CoV-2 antibodies.

The COVID-19 pandemic triggered the development of numerous diagnostic tools to monitor infection and to determine immune response. Although assays to measure binding antibodies against SARS-CoV-2 are widely available, more specific tests measuring neutralization activities of antibodies are immediately needed to quantify the extent and duration of protection that results from infection or vaccination. We previously developed a 'Serological Assay based on a Tri-part split-NanoLuc® (SATiN)' to detect antibodies that bind to the spike (S) protein of SARS-CoV-2. Here, we expand on our previous work and describe a reconfigured version of the SATiN assay, called Neutralization SATiN (Neu-SATiN), which measures neutralization activity of antibodies directly from convalescent or vaccinated sera. The results obtained with our assay and other neutralization assays are comparable but with significantly shorter preparation and run time for Neu-SATiN. As the assay is modular, we further demonstrate that Neu-SATiN enables rapid assessment of the effectiveness of vaccines and level of protection against existing SARS-CoV-2 variants of concern and can therefore be readily adapted for emerging variants.

Evaluation of Three Anti-SARS-CoV-2 Serologic Immunoassays for Post-Vaccine Response.

BACKGROUND: In North America, both messenger RNA (mRNA) vaccines, Pfizer-BioNTech BNT162b2, and Moderna mRNA-1273, each utilizing a 2-dose regimen, have started to be administered to individuals. METHODS: We evaluated the quantitative serologic antibody response following administration of either a single dose or both doses of an mRNA severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine in a cohort of 98 participants (88 healthcare workers [HCW] and 10 solid organ transplant [SOT] recipients). Antibody levels were compared across 3 immunoassays: Elecsys Anti-SARS-CoV-2 S (Roche Diagnostics), SARS-CoV-2 TrimericS IgG (DiaSorin), and SARS-CoV-2 IgG II Quant (Abbott). RESULTS: Among HCW, sensitivity ranged from 100% (Roche), 99% (Abbott) and 98% (DiaSorin). The SARS-CoV-2 IgG II Quant and SARS-CoV-2 TrimericS IgG assays showed good agreement with a Pearson correlation coefficient of R = 0.95. Pearson correlation coefficients of R = 0.82 and 0.83 were obtained for Elecsys Anti-SARS-CoV-2 S vs SARS-CoV-2 TrimericS IgG and SARS-CoV-2 IgG II Quant vs Elecsys Anti-SARS-CoV-2 S, respectively. Significant differences in antibody levels between HCW and SOT recipients were observed. A decrease in antibody levels from time of vaccine administration to blood draw was evident. Among those with a second dose, an increase in antibody levels with increased time between administration of the first and second dose was observed. CONCLUSIONS: The absolute values generated from each of the assay platforms are not interchangeable. Antibody levels differed with increased time between vaccine administration and with increased time between administration of the first and second dose. Further, significant differences in antibody levels between HCW and SOT recipients were observed.

Possible roles of vitamin D in COVID-19

There is emerging interest in the possible connection between vitamin D and SARS-CoV-2 infectious disease (COVID-19). Here, we discuss some hypotheses as to how vitamin D may contribute to the pathophysiology of COVID-19 illness. Vitamin D is thought to be involved in mediating inflammation and regulating the immune system. This may be particularly important in the context of the cytokine storm seen in some cases of COVID-19, which can lead to severe acute respiratory distress syndrome and mortality. We also analyse the potential connection between vitamin D and higher COVID-19 incidence and mortality in areas that receive less sun (higher latitude), and in populations that are known to have low vitamin D levels. On constate un intérêt croissant pour le lien qui pourrait être établi entre la vitamine D et la maladie infectieuse due au SRAS-CoV-2 (COVID-19). Dans cet article, nous nous penchons sur certaines des hypothèses relatives à la façon dont la vitamine D pourrait contribuer à la physiopathologie de la COVID-19. Il a été suggéré que la vitamine D pourrait jouer un rôle dans la réduction de l'inflammation et la régulation du système immunitaire. Cette découverte est particulièrement significative dans le contexte du choc cytokinique observé dans certains cas de COVID-19 et associé à des formes graves du syndrome de détresse respiratoire aiguë, voire au décès de patients. Nous analysons également le lien potentiel entre la vitamine D et les taux supérieurs d'incidence et de mortalité associés à la COVID-19 dans les régions moins ensoleillées (plus hautes latitudes), et au sein des populations reconnues pour leur faible production de vitamine D.