Monovalent WPV induces stronger antibody and HI responses than SV.

(A[i]) Macaques (n = 9 per group) were vaccinated with monovalent A/Singapore/GP1908/2015 (H1N1) WPV or SV followed by a second dose 28 days later. Blood was collected prior to receiving each dose (day 0 pre-bleed and day 28) and at day 56. (A[ii]) List of antigen and strain information used for multiplex analysis. (B) Cytokine levels in plasma obtained at 0, 6 and 24 hours after the first dose. Dotted lines indicate the manufacturer’s theoretical limit of detection. (C) Hemagglutination inhibition (HI) was measured against A/Singapore/GP1908/2015 (H1N1) and A/Singapore/INFIMH-16-0019/2016 (H3N2). Individual HI antibody titres are expressed as reciprocals of the highest plasma dilutions that showed complete inhibition of agglutination. (D) Multiplex analysis of antibody responses in plasma samples against H1N1 and H3N2 antigens. Median fluorescence intensity of IgG, IgA, FcγR2a and FcγR3a binding to HA, NA, NP and HA Stem from H1N1 strains as well as HA and NA from H3N2 strains. Mann-Whitney tests were used to analyse statistical significance between vaccine groups at each time point with the mean±SD in each group shown. Figure created with Biorender.