Protective and antiviral activities of Nigella sativa against avian influenza (H9N2) in turkeys

The main objective of this study was to determine the possible effects of Nigella sativa on immune-response and pathogenesis of H9N2 avian influenza virus in turkeys. The experiment was performed on 130 non-vaccinated mixed-sex turkey poults, divided into five experimental groups of 30 birds each. Group A was kept as non-infected and a non-treated negative control while group B was kept as infected and non-treated positive control. Turkeys in groups A and B received normal commercial feed while turkeys of groups C, D and E were fed on diets containing 2%, 4% and 4% NS seeds, respectively, from day one through the entire experiment period. All groups were challenged with H9N2 AIV at 4th week of age except group A. Infected turkeys showed clinical signs of different severity, showing the most prominent disease signs in turkeys of the group B. All infected turkeys showed positive results for virus shedding; however, the pattern of virus shedding was different, and with turkeys of the group B showing pronounced virus secretion than the turkeys in other groups receiving different levels of NS. Moreover, significantly higher antibody titer against H9N2 AIV in turkeys fed 6% NS seeds shows the immunomodulatory nature of NS. Similarly, increased cytokine gene expression suggests antiviral behavior of NS especially in dose dependent manner, leading to suppressed pathogenesis of H9N2 viruses. However, reduced virus shedding and enhanced immune responses were more pronounced in those turkeys received NS at the rate of 4% and 6%. This study showed that supplement of NS would significantly enhance immune responsiveness and suppress pathogenicity of influenza viruses in turkeys.