shRNA-triggered RNAi inhibits expression of NDV NP gene in chicken embryo fibroblast

Cholesterol 25-hydroxylase inhibits Newcastle disease virus replication by enzyme activity-dependent and direct interaction with nucleocapsid protein

Newcastle disease virus (NDV) is a significant enveloped virus within the Paramyxoviridae family, posing a major threat to the global poultry industry. Increasing evidence suggests that cholesterol-25-hydroxylase (CH25H) and its enzymatic product, 25-hydroxycholesterol (25HC), exhibit broad-spectrum antiviral activity properties by modulating lipid metabolism and various signaling pathways. However, the specific role of CH25H in regulating NDV infection and replication remains unclear. In this study, we demonstrate that CH25H significantly inhibits NDV replication by blocking viral entry through its enzymatic product, 25HC. Notably, a catalytic mutant of CH25H (CH25H-M), which lacks hydroxylase activity, still retains partial ability to inhibit NDV replication, suggesting the involvement of an enzyme-independent antiviral mechanism. Furthermore, we found that CH25H interacts with the viral nucleoprotein (NP), leading to a reduction in NP expression and inhibition of viral ribonucleoprotein (RNP) complex activity. These findings reveal that CH25H exerts antiviral effects through both enzyme-dependent and -independent mechanisms, providing new insights into its role in host defense and offering potential targets for the development of antiviral therapies.IMPORTANCECholesterol 25-hydroxylase (CH25H) is a multifunctional host protein that has been implicated in regulating the life cycles of various viruses. As a prototype of paramyxovirus, Newcastle disease virus (NDV) poses a significant threat to the global poultry industry, causing substantial economic losses. Uncovering the mechanisms of NDV-host interactions is crucial for unraveling the viral pathogenesis and the host immune response, which can drive the development of effective antiviral therapies. Here, we demonstrate that CH25H, whose expression is induced upon NDV infection, plays a pivotal role in restricting viral replication. Specifically, CH25H interacts with the viral NP and inhibits the viral RNP activity. These findings expand our understanding of CH25H's antiviral functions and offer new insights into virus-host interactions, providing potential targets for the development of novel antiviral drugs against NDV and related pathogens.

Newcastle disease virus nucleocapsid protein mediates the degradation of 14-3-3ε to antagonize the interferon response and promote viral replication

Newcastle disease virus (NDV) is responsible for outbreaks that pose a threat to the global poultry industry. NDV triggers an interferon (IFN) response in the host upon infection. However, it also employs mechanisms that counteract this response. One important component in IFN-related signaling pathways is 14-3-3ε, which is known to interact with retinoic acid-inducible gene I (RIG-I) and mitochondrial antiviral signaling protein (MAVS). The relationship between 14 and 3-3ε and NDV infection has not been previously explored; therefore, this study aimed to investigate this relationship in vivo and in vitro using overexpressed and knockdown 14-3-3ε experiments, along with co-immunoprecipitation analysis. We found that NDV infection led to the degradation of 14-3-3ε. Furthermore, 14-3-3ε inhibited the replication of NDV, suggesting that NDV may enhance its own replication by promoting the degradation of 14-3-3ε during infection. The study revealed that 14-3-3ε is degraded by lysosomes and the viral protein nucleocapsid protein (NP) of NDV induces this degradation. It was also observed that 14-3-3ε is involved in activating the IFN pathway during NDV infection and mediates the binding of MDA5 to MAVS. Our study reveals that NDV NP mediates the entry of 14-3-3ε into lysosomes and facilitates its degradation. These findings contribute to the existing knowledge on the molecular mechanisms employed by NDV to counteract the IFN response and enhance its own replication.

Chicken genome editing for investigating poultry pathogens

Major advances in pathogen identification, treatment, vaccine development, and avian immunology have enabled the enormous expansion in global poultry production over the last 50 years. Looking forward, climate change, reduced feed, reduced water access, new avian pathogens and restrictions on the use of antimicrobials threaten to hamper further gains in poultry productivity and health. The development of novel in vitro cell culture systems, coupled with new genetic tools to investigate gene function, will aid in developing novel interventions for existing and newly emerging poultry pathogens. Our growing capacity to cryopreserve and generate genome-edited chicken lines will also be useful for developing improved chicken breeds for poultry farmers and conserving chicken genetic resources.