Zika virus-like particle vaccine fusion loop mutation increases production yield but fails to protect AG129 mice against Zika virus challenge
Fig 4
Lead and F108A VLP induction of nAb after booster immunization. The vaccination schedule is shown in Fig 3A.
(A) NT50 is defined as the reciprocal dilution of serum that neutralizes 50% of reporter virus luminescence calculated using linear regression analysis. Each symbol represents the NT50 for an individual animal, and † indicates a lethal ZIKV infection. Horizontal bars represent the geometric mean titer (GMT) of each group. The dotted line is the limit of detection (LOD) of the assay, and sera with undetectable neutralization activity were assigned a value of one-half LOD (5). Statistical comparisons of NT50 data were performed using Kruskal-Wallis test followed by Dunn’s multiple comparisons tests (*P<0.05; **P<0.01; ***P<0.001; ****P<0.0001; ns, not significant). All VLP groups were compared to the Alum-only group. Additional pairwise comparisons were performed between titers of lead and F108A groups at each dose, with significance level for each comparison shown above each bar. (B) Comparison of NT50 titers for combined lead VLP groups compared to combined F108A VLP groups. GMT, individual NT50 values, assay LOD, † designation, and significance value by Mann-Whitney U test are as in (A). (C) Ab quality assessment by the ratio of NT50 to ELISA titer to lead VLP are shown for each dose of lead or F108A VLP. Group geometric mean titer ratios are shown above each group, individual ratios are shown by a symbol, group means by a horizontal bar, lethal infections by the symbol †, and statistical significance by Kruskal-Wallis followed by Dunn’s multiple comparison tests for each of the three doses as in (A). (D) Ab quality assessment by NT50 to ELISA titer to lead VLP ratios are shown for combined lead and combined F108A groups. Group GMT ratios, individual ratios, lethal infections, and statistical significance levels by Mann-Whitney U test are as in (A).