The P protein T25M substitution is involved in the quasispecies and virulence of Newcastle disease virus

This research investigated the T25M mutation in the P gene of the Newcastle disease virus (NDV)-Spotted Dove strain, which emerged as a significant mutation conferring virulence after 100 serial passages through chicken embryos. The P gene typically encodes a viral phosphoprotein that serves various roles in the viral life cycle, including involvement in viral RNA synthesis, interaction with other viral proteins, and occasionally modulation of the host immune response. A T25M mutation, characterized by the substitution of threonine with methionine at position 25, has the potential to modify the structural configuration of the P gene. The findings highlight the significance of the extensive quasispecies population of NDV, which develops virulence and improves viral replication and transmission in chickens. Key point mutations, particularly T25M in these cases, are essential for viral fitness and the evolution of NDV quasispecies in chicken embryos and DF-1 cells.