Fusion-GEM complexes induce ZIKV-specific IgG and neutralizing antibodies
Fusion-GEM complexes (ZI-△-PA-GEM, ZI-JE-△-PA-GEM and ZI-GP-△-PA-GEM) were chosen for immune evaluation in BALB/c mice (Fig. 3A). There were no abnormality or adverse effects in mice after immunization. ZIKV E-protein-specific IgG could be detected in the serum for at least 8 weeks (Fig. 3B). The serum at week 6 was subjected to a neutralizing antibodies, and the results (Fig. 3C) showed that the mean PRNT50 titers were all above 10, which is the threshold for protection.
IgG2a/IgG1 ratios were usually used in Th1 or Th2 biased detection[16-18]. We next examined the quality of this humoral response by IgG2a and IgG1 subisotype-specific ZIKV-E ELISA at week 6 (Fig. 3D). IgG2a/IgG1 ratios lower than 1.0 indicated that ZI-D/ZI-E induced a Th2-biased response.