Comparative Analysis of Innate Immune Responses after Infection with Newcastle Disease Virus in Layer

Abstract

The current investigation compared the initial immune responses from layer chickens infected with NDV. A total of 60 samples were obtained from several suspect NDV-infected layer flocks of Iraqi farms (age: 36 months; trachea: 30; lung: 30) in the middle of Iraq (Diyala province). The amount of RNA was substantially higher inside the chicken trachea than in its lung tissue. Real-time PCR results showed that 24 NDV was detected in both tissues' samples. The highest viral load was found in tracheal tissues at 6.33×10³ copies/L viral nucleic acid at 7 dpi, whereas the lowest viral load was found in lung tissues at 2.12×10³ copies/L viral nucleic acid at same time. During 3 and 7 days after infection, there were significantly higher (P≤0.05) expressions of IFN-γ, IL-1, and IL-6 in the tracheal tissues than in the lung, indicating up-regulation of these three factors. After an infection, IL18 was not up-regulated simultaneously in either tissue. Moreover, a higher immune response (IFN-γ, IL-1, IL-6, and IL-18) in the trachea compared to the lung was linked to the virus' higher viral RNA levels through elevated expression of the majority of the genes analyzed. Hence, our investigation showed that early host immune reactions to the NDV differed in the trachea as well as lung, the host defenses in chicken will require more research. Findings show that NDV strains produce significant disease in organs that is linked to high viral replication and then innate immune responding.