Figure 1.

Type I IFN suppression supports virus replication and promotes a robust IgG antibody response. (a) Viraemia of ZIKV‐infected type I IFN‐competent (n = 5) and MAR1‐5A3‐treated (n = 5) WT mice. Mice were inoculated with 1 × 10⁶ PFU ZIKV i.v. by the retro‐orbital route. Two mg of MAR1‐5A3 was administered i.p. on the same day as infection. Data shown are expressed as mean ± SD. Statistical significance was measured using Mann–Whitney U‐test between type I IFN‐competent and MAR1‐5A3‐treated WT mice of the same days post‐infection (**P < 0.01). ZIKV virion‐based ELISA was conducted using pooled serum of n = 5 animals from (b) type I IFN‐competent and (c) MAR1‐5A3‐treated WT mice at 1:100 for IgM (top panel) and at 1:500 for IgG (bottom panel) detections. Data are represented as mean ± SEM of three independent experiments with five animals per group per experiment performed in two technical duplicates. (d) Levels of ZIKV‐specific IgG1, IgG2b, IgG2c and IgG3 were assessed by purified ZIKV virion‐based ELISA using pooled serum from n = 5 mice of respective groups collected at 4, 12 and 45 dpi. ZIKV‐specific IgG subtypes are expressed as antibody titre, defined as the greatest reacting dilution before the OD value reaches baseline control (pooled 0 dpi sera). ND, not detectable.