Figure 7

Photomicrographs of hematoxylin-and eosin-stained intestinal sections of chickens on 4^th day post-challenge. Chickens (N = 12) were immunized with Sal-vector, Sal-HA, Sal-M2e, Sal-M2e-NA or Sal-HA-M2e-NA vaccine, and 28 days later all the immunized chickens were challenged with 1.4 × 10⁴ TCID₅₀ H7N9 virus. At 4^th day post challenge, chickens (n = 3) were sacrificed and intestinal tissues were collected for histological analysis.