Journal: Scientific Reports

Article Title: An engineered vaccine of the Plasmodium vivax Duffy binding protein enhances induction of broadly neutralizing antibodies

doi: 10.1038/s41598-017-13891-2

Figure Lengend Snippet: Inhibition of DBPII binding to DARC on human erythrocytes by standard COS7 cell assay. Antisera were tested for inhibition of DBPII-Sal1-erythrocyte binding ( a ) and three naturally occurring variant DBPII alleles (Spplementary Fig. ) by end point dilution. Each curve on the chart represents non-linear regression of two independent experiments, with each dilution tested in triplicate and horizontal broken line shows the 50% inhibition (IC50). Graph was constructed using GraphPad Prism software. ( b ) Quantitative comparison of anti-DBPII inhibitory activity of the different sera against variant DBPII alleles based on the IC50 serum dilution. Error bars represent ± SD.

Article Snippet: A non-linear regression was used to provide the dose-response curves for the anti-DBPII inhibitory concentrations (GraphPad).

Techniques: Inhibition, Binding Assay, Variant Assay, Construct, Software, Activity Assay

Journal: Scientific Reports

Article Title: An engineered vaccine of the Plasmodium vivax Duffy binding protein enhances induction of broadly neutralizing antibodies

doi: 10.1038/s41598-017-13891-2

Figure Lengend Snippet: Multiple comparisons of anti-DBPII binding-inhibitory responses. The overall inhibitory response of each antiserum against all four COS7 cell-expressed DBPII alleles was compared with Dennett’s adjustment multiple comparisons, with Sal1 as control. Bars represent the mean IC50 value of each serum dilution against all the variant DBPII alleles tested in the COS7 assay. Sera were placed into three groups (DEKnull-2, Sal1/DEKnull, and DEKnull-4). Asterisk (*) indicates a significant difference in the inhibitory responses between the immune sera from the DEKnull-2 group and the DEKnull/Sal1 group and the DEKnull-4 group ( p = 0.05).

Article Snippet: A non-linear regression was used to provide the dose-response curves for the anti-DBPII inhibitory concentrations (GraphPad).

Techniques: Binding Assay, Variant Assay

Journal: Scientific Reports

Article Title: An engineered vaccine of the Plasmodium vivax Duffy binding protein enhances induction of broadly neutralizing antibodies

doi: 10.1038/s41598-017-13891-2

Figure Lengend Snippet: Naturally acquired immune response and anti-DBPII binding-inhibitory antibodies (BIAbs). ( a ) Plasma from study participants were screened for binding inhibitory antibodies (BIAbs) by COS7 cell assay. Non-responders (NR), had no BIAbs; Temporary responders (TP), had variable BIAbs; Persistent responders (PR), had BIAbs during all three cross-sectional surveys in the 1 st year, while Elite responders (ER), had BIAbs during all three cross-sectional surveys in the 1 st year and six years later. ( b ) IgG antibody profiles of individuals with long-term persistent antibody responders (ER) against naturally occurring DBPII Sal1, Brz1 and DEKnull-2. ( c ) K-means clustering analysis based on ELISA reactive index (RI) and BIAb activity of individual responses in each cohort during follow up from year one up till year six (n = 224) identifies three distinct clusters: 1. Low-responders, low RI and BIAbs (n = 173); 2. Moderate-responders, moderate RI and BIAbs (n = 34); and 3. High-responders, high RI and BIAbs (n = 17). ( d ) Total IgG specific antibodies to DBPII variants (Sal-1 and Braz1) and synthetic DEKnull-2 among the high (black cycle) and moderate-response groups (white cycle); Asterisk (*) indicates a significant difference between groups (p < 0.05; determined by Kruskal–Wallis test with Dunn’s post-test), with medians for high and moderate-response clusters represented by continuous or discontinuous lines. ( e ) Inhibition of P . vivax invasion of human reticulocytes by anti-DEKnull-2 and anti-DBPII-Sal1. Invasion was determined by analyzing newly invaded rings in wells of culture plates in the presence of antibodies relative to wells with no antibodies. The bars represent mean percentage invasion-inhibition against all three different isolates and error bars represent ± standard deviation. (nd: not done). ( f ) Differences in amino acid residues in DBPII between the three field isolates relative to the Sal1 reference sequence.

Article Snippet: A non-linear regression was used to provide the dose-response curves for the anti-DBPII inhibitory concentrations (GraphPad).

Techniques: Binding Assay, Enzyme-linked Immunosorbent Assay, Activity Assay, Inhibition, Standard Deviation, Sequencing