Fig. 8. Correlation analysis between functional antibody responses and vaccine efficacy parameters.

a Correlation between VN-, NI-, and HI-titer and virus replication in the lung, fever, and pathology visualized by interpolation (dashed line) using the sigmoid emax model for virus titers and RLW and the Emax model for fever. Antibody titers were determined at the day of challenge (day 37). Vaccine treatment is indicated by shape and color. R² indicates the goodness of the fit. Lung viral titers were selected because the lung is the organ of direct vital importance and should be protected. Fever and relative lung weight (lung pathology) as clinical and pathological parameters were preferred, because they contained more measurements and/or are not based on a subjective scoring system. b Correlation between the different antibody titers at day of challenge visualized by interpolation using the sigmoid Emax model.