Figure 4.

MERS-CoV-specific antibody responses

Dots represent data from individual participants, and the median is depicted by horizontal line within the boxes. Error bars represent minimum to maximum values. (A) Binding antibodies were measured against the MERS-CoV S1 protein using an in-house ELISA. The horizontal dashed line depicts the positive threshold. The optical density value of 0·5 was considered to be the threshold for seropositivity. (B) MERS-CoV-specific neutralising antibody responses were measured by the virus neutralisation test assay after prime and boost immunisation. Data are represented as reciprocal neutralisation titre. The geometric mean of four replicates per participant per timepoint is shown. The signal from samples with no neutralising capacity was set to 1. The horizontal dashed line represents the positive threshold. (C) PRNT titre was calculated on the basis of 80% or greater reduction of infected cells. Data are shown as reciprocal titre. The horizontal dashed line represents the positive threshold. (D) Correlation analysis between binding antibodies (optical density value) and reciprocal PRNT₈₀ titres at day 35 after vaccination. MERS-CoV=Middle East respiratory syndrome coronavirus. PRNT₈₀=plaque reduction neutralisation test titre calculated on the basis of 80% or greater reduction of infected cells.