Journal: Frontiers in Immunology

Article Title: Multiplexed Microsphere-Based Flow Cytometric Assay to Assess Strain Transcending Antibodies to Plasmodium vivax Duffy Binding Protein II Reveals an Efficient Tool to Identify Binding-Inhibitory Antibody Responders

doi: 10.3389/fimmu.2021.704653

Figure Lengend Snippet: Standardization of DBPII-multiplexed microsphere-based cytometric assay. (A) Titration curve for anti-DEKnull-2 antibodies in plasma samples (1:50–102,400) from DBPII-negative pool from individuals living in a nonendemic area of malaria (gray), DBPII-negative pool from an endemic area (blue), and DBPII-positive pool obtained from malaria-exposed individuals who have BIAb response as determined by the reference method of the COS-7 cells (red). The highlighted rectangle represents the selected plasma dilution (1:800). The delta value (Δ) corresponds to the difference in the mean fluorescence intensity (MFI) between the positive pool from malaria-exposed individuals and the pool from nonexposed individuals. (B, C) Titration curve of MFI to monoclonal antibodies (mAbs; 0.2–0.006 μg/ml) or plasma-pooled samples (1:200–6,400). Inhibitory mAb 2D10 was represented by a light-green diamond and noninhibitory mAb 3D10 by a dark green triangle. Plasma pooled from individuals living in a nonendemic area are represented with a gray line and positive pooled samples with a red line. The MFI values were obtained using the FlowJo program (version 10.4.1) according to the analysis strategy described in Figure S1 .

Article Snippet: To compare the performance between simplex and multiplex versions of multiplexed microsphere-based flow cytometric assays, receiver operating characteristic (ROC) curves were constructed using GraphPad Software.

Techniques: Titration, Clinical Proteomics, Fluorescence, Bioprocessing

Journal: Frontiers in Immunology

Article Title: Multiplexed Microsphere-Based Flow Cytometric Assay to Assess Strain Transcending Antibodies to Plasmodium vivax Duffy Binding Protein II Reveals an Efficient Tool to Identify Binding-Inhibitory Antibody Responders

doi: 10.3389/fimmu.2021.704653

Figure Lengend Snippet: DBPII multiplexed microsphere-based cytometric assay in Plasmodium vivax plasma samples from individuals previously characterized as DBPII high responders (HR), non-responders from the malaria-endemic area (NR) or non-exposed (NE). Scatter plots of mean fluorescence intensity (MFI) for individual samples (n = 76) from the endemic area performed with the cytometric bead-based assay multiplex to DEKnull-2 (A) , and native DBPII (B, C) . The samples were classified according to tercile intervals of reactive index (IR) of ELISA response and inhibitory response (BIAbs) evaluated by COS-7 assay as: High reactive (HR, n = 21), IR ≥ upper tercile and high inhibitory response (black circles); non-responders (NR, n = 42), who presented IR < 1 and negative inhibitory response (dark gray circles) and non-exposed (NE, n = 13), represented by individuals from a non-endemic area (white circles). Median and interquartile range (IQR) values are represented for each group.

Article Snippet: To compare the performance between simplex and multiplex versions of multiplexed microsphere-based flow cytometric assays, receiver operating characteristic (ROC) curves were constructed using GraphPad Software.

Techniques: Clinical Proteomics, Fluorescence, Bead-based Assay, Multiplex Assay, Enzyme-linked Immunosorbent Assay

Journal: Frontiers in Immunology

Article Title: Multiplexed Microsphere-Based Flow Cytometric Assay to Assess Strain Transcending Antibodies to Plasmodium vivax Duffy Binding Protein II Reveals an Efficient Tool to Identify Binding-Inhibitory Antibody Responders

doi: 10.3389/fimmu.2021.704653

Figure Lengend Snippet: Association between DBPII antibody response as detected in the DBPII-multiplexed microsphere-based cytometric assay and BIAbs as determined by standard COS-7 cytoadherence assay. Two-hundred and forty-five plasma samples of P. vivax -exposed individuals were screened for (i) antibodies targeting DBPII-DARC interaction (BIAbs) using the COS-7 cell erythrocyte-binding assays and (ii) anti-DBPII antibody responses as detected by the DBPII-based multiplex assay. The relative likelihoods of positivity in the multiplex assay corresponding to the presence of BIAbs (dependent variable used as reference) were calculated according to the number of DBPII proteins recognized in the DBPII-multiplex assay, including none (zero), one (1), two (2), or three (3). Odds ratio (OR) with respective 95% confidence intervals (95% CI) and p -values were determined using the logistic regression model with multiplex seropositivity against none, one, two, or three recombinant proteins used as confounding variables.

Article Snippet: To compare the performance between simplex and multiplex versions of multiplexed microsphere-based flow cytometric assays, receiver operating characteristic (ROC) curves were constructed using GraphPad Software.

Techniques: Clinical Proteomics, Binding Assay, Multiplex Assay, Recombinant