Fig 1: Workflow and performance of C19BA.a Overview of the detection of SARS-CoV-2 seroconversion by flow-cytometric bead array. Streptavidin-coated microbeads with different fluorescence intensities are conjugated with recombinant biotinylated viral antigens (RBD, S1, and N) and mixed and incubated with pre-diluted serum samples together with control beads. After incubation, microbeads are washed and stained with anti-human IgG and IgM secondary antibodies, washed, and acquired on a flow cytometer for downstream analysis. Schematic created using BioRender.com. b Dot plots showing the staining patterns of positive (red) and negative (black) control beads with secondary anti-IgG-PE, anti-IgM-BV421, or both. The signal corresponding to IgG-PE (top) and IgM-BV421 (bottom) is shown for each column. c Histogram showing the distribution of the microbeads based on their intrinsic fluorescence on the APC channel. Each colour represents the coating for each microbead. d Representative dot plots showing the specificity of the staining pattern of recombinant anti-RBD IgG (left) or anti-N IgG (right) antibodies.
Fig 2: Identification of SARS-CoV-2 IgG and IgM seroconversion by C19BA.a Titration curves of the reactivity of individual serum samples against RBD, S1, and N proteins measured by flow cytometry against IgG by C19BA (top) and ELISA (bottom) for each cohort: preCOVID (red, n = 10) and COVID (black, n = 10). COVID serum samples were obtained at time of hospital admission (PCR+). b AUC values for the experiment shown in a. c Titration curves of the reactivity of individual serum samples against RBD, S1, and N proteins against IgM by C19BA (top) and ELISA (bottom). d AUC values for the experiment shown in c. Statistical analyses were performed using an unpaired two-tailed Student’s t-test. Asterisks represent p values (***p < 0.001, *p < 0.05, ns not significant). Horizontal lines represent median values.
Fig 3: C19BA reveals different serology patterns in preCOVID and COVID samples collected at time of hospital admission (PCR+).Dot plots showing IgG (top) and IgM (bottom) reactivity against RBD, S1, and N for representative preCOVID and COVID samples.
Fig 4: C19BA identifies IgG and IgM seroconversion in a cohort of samples from convalescent donors, and the presence of N-reactive IgG antibodies in Covid-seronegative samples.a Serological responses against RBD, S1, and N measured by C19BA on serum samples (n = 38) from convalescent patients after at least 1 month of disease onset, IgG (top) and IgM (bottom) are shown. b Representative dot plots obtained by C19BA showing IgG (top) and IgM (bottom) levels, as indicated. Statistical analyses were performed using an unpaired two-tailed Student’s t-test. Asterisks represent p values (****p < 0.0001, ***p < 0.001, **p < 0.01). Horizontal lines represent median values.
Supplier Page from Novus Biologicals, a Bio-Techne Brand for Human IgM Isotype Control [Biotin]
Available conjugates: Biotin