The Ntail region of nucleocapsid protein is associated with the pathogenicity of pigeon paramyxovirus type 1 in chickens

The nucleoprotein (NP) of pigeon paramyxovirus type 1 (PPMV-1) and other paramyxoviruses plays an important role in virus proliferation. A previous study found that NP is associated with the low pathogenicity of PPMV-1 strains in chickens. Here, we investigated which domain of NP is responsible for regulating the pathogenicity of PPMV-1. We found that the Ntail sequences were more diverse for different viral genotypes compared to Ncore sequences. The chimeric rBJ-SG10Ntail strain caused more severe clinical symptoms than the parental rBJ strain, increased the viral copy number in sampled tissues and induced higher IFN-γ gene expression. This demonstrated that the Ntail sequence plays a role in regulating viral virulence. These findings increase our understanding of the Ntail of NP protein and the virulence factors associated with PPMV-1.