Cholesterol 25-hydroxylase inhibits Newcastle disease virus replication by its architectural damage and blocking HN protein

Cholesterol 25-hydroxylase (CH25H) is a membrane-bound endoplasmic reticulum protein that converts cholesterol into 25-hydroxycholesterol (25HC). Recent studies showed that CH25H is an interferon-stimulated gene (ISG) that helps fight various viruses and has broad antiviral effects. However, the role of chicken CH25H (chCH25H) in controlling Newcastle disease virus (NDV) infection and replication remains unexplored. This study examined the impact of chCH25H on NDV infection in chicken embryo fibroblast cells. The results showed that cells try to upregulate the chCH25H expression temporally upon viral infection. Moreover, the overexpression of chCH25H reduced NDV infection in cells while reducing endogenous chCH25H levels increased its replication. Additionally, treating cells and viruses with 25HC, an active metabolic intermediate of chCH25H, significantly reduced NDV replication by blocking the virus from entering cells while causing significant structural damage to the virus architecture. In addition, in ovo results also exhibited that the eggs treated with lipopolysaccharides (LPS), a positive regulator of chCH25H and 25HC, resulted in extensive viral reduction. These findings indicate that chCH25H and 25HC are against NDV replication in chicken fibroblast cells.