Figure 3. Immune responses after viruses challenge in chickens.

(A) The frequency of IFN-γ⁺CD4⁺ or IFN-γ⁺CD8⁺ T cells in lungs. Chickens in groups of five were vaccinated with mock vaccine or SD/01/10-ca on day 0 and challenged intranasally with 10⁶ EID₅₀ of A/chicken/Hebei/YT/2010 on day 14 after vaccination. Lungs were harvested on day 7 after challenge. IFN-γ⁺CD4⁺ or IFN-γ⁺CD8⁺ T cells in lungs stimulated with SD/01/10-wt were measured. Percentages of IFN-γ⁺CD4⁺ or IFN-γ⁺CD8⁺ T cells within CD4⁺ or CD8⁺ T cells were analyzed. *P < 0.05, by one-way analysis of variance of the difference between SD/01/10-ca and mock vaccine group on day 7 after challenge. (B) HI antibody responses to homologous and heterologous viruses after vaccination with SD/01/10-ca. Serum samples were collected on day 14 post immunization, and the reactivity of collected sera (n = 3) to SD/01/10-wt or five heterologous H9N2 influenza viruses was assessed by an HI assay. Abbreviations: BJ, Beijing; Ck, chicken; GD, Guangdong; HeB, Hebei; SD, Shandong.