Positive regulation of humoral and innate immune responses induced by inactivated Avian Influenza Virus vaccine in broiler chickens.

Avian Influenza (AI) vaccines are widely used for mammals and birds in a trial to eliminate the Avian Influenza virus (AIV) infection from the world. However and up till now the virus is still existed via modulation of its antigenic structure to evade the pressure of host immune responses. For a complete understanding of the immune responses following AI vaccination in chickens, the modulations of the chickens humoral immune responses and interferon-alpha signaling pathway, as a fundamental part of the innate immune responses, were investigated. In our study, we measured the humoral immune response using hemagglutination-inhibition (HI) and enzyme-linked immunosorbent assay (ELISA) tests. In addition, chicken interferon-alpha pathway components was measured at RNA levels using Quantitative Real-time PCR (qRT-PCR) following one dose of inactivated H5N1 influenza vaccine at 14 days of age. In this study, the protective levels of humoral antibody responses were observed at 14, 21 and 28 days following immunization with inactivated (Re-1/H5N1) AI vaccine. In the chicken spleen cells, up regulation in the chicken interferon-alpha pathway components (MX1 & IRF7) was existed as early as 48 h post vaccination and remained until 28 days post vaccination at the endogenous state. However, after the recall with ex-vivo stimulation, the up regulation was more pronounced in the transcriptional factor (IRF7) compared to the antiviral gene (MX1) at 28 days post vaccination. So far, from our results it appears that the inactivated H5N1 vaccine can trigger the chicken interferon-alpha signaling pathway as well as it can elicit protective humoral antibody responses.