An Inactivated Novel Genotype Fowl Adenovirus 4 Protects Chickens against the Hydropericardium Syndrome That Recently Emerged in China

Figures

• 

  Figure 1. Fowl adenovirus (FAdV)-specific antibody responses induced 7 days and 14 days post single and double immunization. Chickens in the Single immunization (IM) group produced higher antibody response than the Negative Ctrl. group (p < 0.01), and the double immunization boosted the immune response more than single immunization (p < 0.01). Significant differences between different experimental groups were evaluated at (** p < 0.01).

• 

  Figure 2. FAdV-4 specific T helper 1 (Th1)/Th2 cytokines responses. Th1 (interferon (IFN)-γ) and Th2 (interleukin (IL)-4) cytokines in serum of chickens were detected by ELISA. A strong Th2 response was induced in the vaccinated chickens. Significant differences between Th1 and Th2 cytokines (IFN-γ and IL-4) were evaluated at (* p < 0.05) or (** p < 0.01).

• 

  Figure 3. Protective efficacy of the vaccine in challenge experiment. (A) Survival rates of chickens in the immunized groups, challenge control group and negative control group; (B) The survival curve of the challenge experiment. Significant differences were evaluated at (** p < 0.01).

• 

  Figure 4. Virus shedding in chickens of different groups at 5 days post infection. Significantly higher levels of virus were detected in different tissues of the chickens in the Infection Ctrl. group. There was no significant difference between chickens in the two immunized groups and the Negative Ctrl. group. Significant differences between different experimental groups were evaluated at (* p < 0.05) or (** p < 0.01).

• 

  Figure 5. Histopathology in tissues at 5 days post challenge (hematoxylin and eosin (HE) stain). There was no significant histopathology change in tissues of chickens in the Negative Ctrl. group (A–F), Single IM group (M–R), and Double IM group (S–X). Massive pathological damages were observed in chickens of the Infection Ctrl. group: (G) severe edema and a small amount of inflammatory cells appeared in the epicardium of the heart. (H) Degeneration, vacuolar necrosis and basophilic inclusion bodies presented in liver cells. (J) no obvious changes showed in the kidney. (K) Large numbers of macrophage proliferations and cortical lymphocyte depletion appeared in the thymus. Severe reduction and necrosis of lymphocytes showed in the spleen (I) and bursa (L).