Abstract
Newcastle disease, caused by virulent strain of Newcastle disease virus (NDV), is an acute, highly contagious disease that is prevalent worldwide and is responsible for serious economic losses to the poultry industry. In the current study, we compared the early immune responses in chickens infected with two strains of velogenic NDV, a duck origin, named GD strain (Md/CH/LGD/1/2005, genotype VIId), and an chicken origin, F48E9 strain (genotype IX). The viral RNA level of GD strain was significantly higher than those of F48E9 in most tissues of chicken. Furthermore, the high level of viral RNA of the GD strain was associated with a stronger immune response compared to that of F48E9, characterized by upregulated expression of some of avian β‐defensins and cytokines, most of toll‐like receptors, and some of the other immune‐related genes investigated. This study thus demonstrated differences in host early immune responses to the two NDV strains. Further studies are needed to characterize the basic molecular mechanisms involved in the host responses in chickens infected by the two NDV strains.
Highlights
Newcastle disease (ND) is one of the most important viral diseases affecting birds worldwide, and is responsible for serious economic losses to the poultry industry due to high mortality, decreased egg production, and body weight loss (Alexander, 1997)
A ND virus (NDV) strain JS5/05 produced more severe damage to the lymphatic organs in chickens compared to Herts/33 strain and F48E8 strain, due to the high viral load and strong immune response induced by JS5/05 strain (Hu et al, 2015)
We evaluated the molecular bases of the different immune responses induced by two NDV strains, GD and F48E9 by measuring the viral RNA and expression patterns of avian β-defensins (AvBDs), Toll-like receptors (TLRs), cytokines, and other immune-related genes in the tissue samples of chickens during the early stage of infection
Summary
Newcastle disease (ND) is one of the most important viral diseases affecting birds worldwide, and is responsible for serious economic losses to the poultry industry due to high mortality, decreased egg production, and body weight loss (Alexander, 1997). A NDV strain JS5/05 (genotype VIId) produced more severe damage to the lymphatic organs in chickens compared to Herts/33 strain (genotype IV) and F48E8 strain, due to the high viral load and strong immune response induced by JS5/05 strain (Hu et al, 2015) These findings indicated that differential regulation of the host immune response by different NDV strains is an important aspect of NDV pathogenesis. We evaluated the molecular bases of the different immune responses induced by two NDV strains, GD (a genotype VIId strain,isolated from the kidney of a diseased white Muscovy duck during an outbreak in 2005) and F48E9 by measuring the viral RNA and expression patterns of avian β-defensins (AvBDs), TLRs, cytokines, and other immune-related genes in the tissue samples of chickens during the early stage of infection
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