Cytokine immune response following vaccination against Fowl Pox disease in Specific Pathogen Free chickens

Fowlpox is an infectious disease with a relatively slow spread in all ages of poultry and is characterized by skin lesions in dry form or diphtheria-like lesions in the mouth in wet form. The disease causes slow growth and reduced egg production. This disease is one of the oldest known poultry diseases. Its virulence first was shown in 1902 by Marks & Sticher. The disease is widespread in all parts of the world and birds of any age, race and gender are susceptible to this virus and are also relatively sensitive. The present study was conducted to investigate Th1 and Th2 cells, respectively, cytokines IFN-γ and IL-4 in the culture medium supernatant of peripheral blood mononuclear cells stimulated with ConA mitogen in vaccinated and control chickens. This study included three groups of 40 21-day-old specific pathogen free chicks. One group was inoculated with PBS and served as a negative control, and the other two groups were vaccinated with Razi institute fowl pox vaccine and a commercial fowl pox vaccine. The injection of vaccine was done in the wing. All chicks were kept for 5 weeks after inoculation. Blood samples of each group were collected weekly up to 5th weeks after vaccination. Peripheral blood mononuclear cells (PBMC) were isolated from each blood sample using centrifuge ficoll-hippopotamus. The concentration of inflammatory cytokines (IFN-γ) and anti-inflammatory (IL-4) in peripheral blood mononuclear cells was measured using ELISA method. Statistical analysis and quantity (P <0.05) were used to evaluate the significant difference between the groups. The results of this study showed that 7 days after vaccination, 90 to 100% of the vaccinated birds had swelling at the injection site. The ratio of the concentration of IFN-γ to IL-4 in supernatant was higher in the cell culture of vaccinated chicks than in the control group. The study states that induction of enhanced immune responses after fowl pox vaccination is mainly due to the Th1-lymphocytes response.