Effects of Nigella sativa on immune responses and pathogenesis of avian influenza (H9N2) virus in turkeys

The main objective of this study was to determine the effects of various levels of dietary Nigella sativa seeds on immune-responsiveness and pathogenesis of H9N2 avian influenza virus (AIV) in turkeys. The experiment was performed on 80 unvaccinated turkey poults, divided into four groups of 20 birds each. Group A was kept as a non-infected, non-treated negative control; group B was inoculated intranasally with H9N2 AIV (106 EID50) at 4 wk of age; groups C and D were fed on diets containing 1% and 3% Nigella sativa seeds, respectively, from d 1 through the entire experiment period and inoculated intranasally with H9N2 AIV (106 EID50) at the wk 4 of age. Infected birds showed clinical signs of differing severity, with the most prominent disease signs appearing in birds of the H9N2 group. All infected birds showed positive results for virus shedding; however, the pattern of virus shedding was different, with birds of group B showing more pronounced virus secretion than the birds in the groups C and D, which were fed different levels of N. sativa. Moreover, significantly higher antibody titer against H9N2 AIV in group D birds show the immunomodulatory nature of N. sativa. Similarly, increased IFN-γ mRNA expression suggest antiviral behavior of N. sativa, leading to suppressed pathogenesis of H9N2 viruses in N. sativa-fed birds.This study showed that dietary supplementation with N. sativa seed at the level of 3% would enhance immune responsiveness and suppress pathogenicity of influenza viruses in turkeys.