Figure 2. ZIKV TCI-DNA vaccine protected adult male and female Ifnar1^−/− mice against ZIKV challenge with complete survival and reduced viral titers, including reproductive organs.

Equal numbers of male and female Ifnar1^−/− mice were immunized with ZIKV E ectodomain, EDI/II peptides, TCI-DNA, or PBS control, and sera were collected at 10 days post-second immunization.

(A and B) At 13 days post-second immunization, the mice were challenged (i.p.) with ZIKV (strain R103451, 10³ PFU/mouse) and recorded for weight (A) and survival (B) daily for 14 days (n = 6).

(C) In a separate experiment, the immunized Ifnar1^−/− mice were challenged with ZIKV (strain PAN2016, 10³ PFU/mouse), and 6 days later, sera and tissues (including brain, kidney, lung, heart, liver, spleen, muscle, and testis) were collected for detection of viral titers using plaque-forming assay. The detection limit was 25 PFU/ml (for sera), 12.5 PFU/g (for brain), 20 PFU/g (for kidney, spleen, and muscle), and 25 PFU/g (for lung, heart, liver, and testis).

The data are represented as mean ± SEM (n = 3 for testis and n = 6 for other groups). *p < 0.05; **p < 0.01; ***p < 0.001.