Table 1.
Sample and donor characteristics.
Fig 1.
Illustration detailing the immunoglobulin G capture assay (G capture) and the double antigen binding assay (DABA).
The G Capture solid phase (cross hatched) is coated with rabbit anti-human gamma FC to capture G from the clinical sample in the first step of the assay. After washing, conjugate is applied and specific antibody (Y) revealed by ZIKA virus NS1 antigen (ZKVNS1Ag) labelled with horseradish peroxidase (HRPO; Z *, standard). The DABA solid-phase is coated with ZKVNS1Ag to capture antibody to NS1Ag of any class. After washing, conjugate is applied and bound antibody (Y) revealed by ZKV NS1Ag labelled with HRPO as above.
Fig 2.
EuroimmunZ vs Unquenched DABA reactivity in pre-Zika era panels.
Plot of sample to cut off (S/CO) ratios of 147 pre-Zika era samples tested in un-quenched DABA and EuroimmunZ. Fourteen samples with EuroimmunZ ratios <1.1 were considered indeterminate by EuroimmunZ criteria. Three samples were reactive by DABA alone. Solid lines represent the cut off value for each assay. Trend line is displayed.
Fig 3.
Antibody reactivity across three assays in samples from PCR confirmed Zika cases.
Venn plots for 91 samples from patients with PCR confirmed ZKV infection. Samples giving sample to cut off ratios >1.0 were defined as reactive. The right hand plot shows reactivity for the panel of 91 samples tested in the three different assays. The three panels on the left in vertical order show the reactivity broken down into the first week, second to fourth week and one or more year after onset of symptoms. The individual reactivity of samples in each test is shown and the overall reactivity for each assay displayed.
Fig 4.
4A and 4B. G capture and DABA data on Zika confirmed panels comparing DV3NS1Ag quenched and un-quenched conjugates. X by Y plots of sample reactivity from patients known to have been infected with ZKV. Reactivity is expressed as sample to cut off ratios when tested using un-quenched conjugate and rDV3NS1Ag-quenched conjugate. Left hand panel (A) displays the results with 59 ZKV convalescent sera (São Paulo and Rio de Janeiro) tested in the DABA using either unquenched or quenched conjugates. Dotted line is a line of interpolated equivalence assuming no difference in reactivity. Solid lines represent the assay cut off values. Right hand panel (B) similarly displays the reactivity of 41 samples from patients with confirmed ZKV infection tested in the G capture using unquenched and quenched conjugate diluents. Samples from patients with proven ZKV showing a reduced reactivity resulting from the quenched conjugate are circled in both panels.
Table 2.
Quenching of non-specific antibody reactivity using a panel of Dengue serotype 1 to 4 antigens.
Table 3.
Titration of un-labelled competitor homologue quadrivalent DV NS1 quench.
Fig 5.
5A and 5B. Antibody reactivity in Dengue quadrivalent antigen quenched assay: comparison with unquenched DABA and EuroimmunZ. X by Y plots of reactivity displayed by 87 selected samples (São Paulo and Rio de Janeiro) drawn from the pre ZIKA-era panel expressed as sample to cut off ratios. Left hand panel (A) displays the results with sera tested in DABA using both quad quenched and unquenched conjugates. Right hand panel (B) similarly displays the reactivity of the same samples tested in quad quenched DABA and EuroimmunZ.
Fig 6.
Zika seroconversion panels: EuroimmunZ vs Quadrivalent antigen quenched G capture by time from infection.
X by Y plots of sample reactivity, expressed as sample to cut off ratios in G capture assay using quad quenched conjugate and in EuroimmunZ, of 38 samples grouped by time since onset of symptoms.
Table 4.
Zika and Dengue antibody reactivity in samples from UK returning travellers.