The deletion of an extra six nucleotides in the 5′ -untranslated region of the nucleoprotein gene of Newcastle disease virus NA-1 decreases virulence
The virulent Newcastle disease virus (NDV) strain NA-1 (genotype VII) was isolated from an epizootic involving a flock of geese in Jilin Province, Northeast China, in 1999. Compared with the classical NDV stra...