Figure 3. CD8⁺ T cells are required for ZIKV efficacy in mice during rechallenge.

(A) Scheme of tumor rechallenge experiments. (B and C) Surviving mice from GL261 studies with ZIKV were rechallenged 3 months (B) (n = 9–10) or 18 months later (C) (n = 8) with 4 × 10⁴ GL261 cells on the contralateral side. Age-matched (20 months old, n = 10; and 26 months old, n = 8) naive mice served as controls. (D) Surviving mice from GL261 studies with ZIKV were rechallenged 3 months later with 4 × 10⁴ GL261 cells and treated with antibodies against CD8 or isotype control as described in the Methods. Age-matched (20 months old; n = 7) mice served as controls. (E) Photon flux (photons/s) of bioluminescent images of brains of mice described from C at indicated times after rechallenge. (F) Representative images from C of hematoxylin and eosin staining of coronal brain sections from a mouse that did not survive rechallenge (mouse 1) and those surviving up to day 150 after rechallenge (mice 2–4). Scale bars represent 1000 μm. Horizontal lines indicate median values. The dotted line denotes the limit of detection (E). Statistical differences were determined by (B–D) log-rank test: ***P < 0.001, ****P < 0.0001; and (E) Mann-Whitney U test: ***P < 0.001. Data are pooled from at least 2 independent experiments.