Effects of Newcastle Disease Infection on the mRNA Expression of Inflammatory Biomarkers in Naturally Infected Chicks
Effects of Newcastle Disease Infection on the mRNA Expression of Inflammatory Biomarkers in Naturally Infected Chicks
Hakeem Jawad Kadhim1, Abbas Kamil Shlaga1*, Safaa Hussein Ali2
ABSTRACT
The Newcastle disease (ND) has a profound impact on the poultry health, causing substantial economic losses due to high mortality. Consequently, despite the implementation of intensive vaccination programs, many flocks still experience clinical signs of ND virus infection. In this study, we aimed to detect the ND virus and characterize the associated inflammatory response in naturally infected broilers. Utilizing RT-PCR, the expression of the matrix (M) gene of NDV and inflammatory biomarkers, including C-reactive protein (CRP), interleukin 6 (IL-6), interleukin-1 beta (IL-1β), and gamma interferon (IFN-γ) genes were analyzed. There were ninety birds used in the study; sixty samples were collected from infected flocks and assigned as an infected group, while thirty samples were gathered from healthy (uninfected) flocks and considered as a control group. Samples, including blood, liver, and tracheal swabs, were collected from 3 to 5 weeks old broilers. The infected birds showed various signs and postmortem lesions, such as mottled spleen and hemorrhages in the proventriculus and cecum. The NDV infection was confirmed using the NDV rapid test, which showed positive results in 52 out of 60 suspected samples (86.66%). Furthermore, RT-PCR data revealed that only 27 (51.92%) out of 52 samples were positive for the M gene. Thereafter, the mean antibody levels of ND-infected birds were significantly lower than those of uninfected birds. In contrast, inflammatory biomarkers’ gene expression exhibited an increase in their mRNA levels, indicating that the birds were infected with a viral infection and that there is inflammation in the body. In conclusion, the M gene could be used as a marker for identifying NDV in infected birds. Similarly, the NDV infection led to a decrease in antibody titers, which is associated with an increase in the gene expression of inflammatory biomarkers in infected birds. Therefore, serological tests as well as the molecular approach should always be considered in endemic regions.
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