[Sequence analysis of the fusion (F) protein genes of four Newcastle disease virus strains causing clinical disease in geese].
Four strains of Newcastle disease virus(NDV), which have proven to be responsible for the disease outbreaks in south and east China regions called "geese paramyxovirus infection" or "avian paramyxovirus infection of geese", were examined for the features of their fusion(F) protein genes. A 1700 nucleotides(nt) fragment of the F gene (1705 nt) of each of the 4 strains were sequenced, the results revealed that the NDV strains of goose origin share common transcriptional sequence and translational start position with the hitherto reported NDV, the F gene homologies among the 4 strains were 97.8%-98.9%, while the corresponding homologies between these strains and the standard challenge strain F48E8 were only 86.0-86.8%. The deduced amino acid sequences near cleavage site of F0 proteins showed a 112RRQKR/F117 motif, comforming well with that of the virulent strains. The cleavage sites distribution of 3 restriction enzymes(Hinf I, Basto I, Rsa I) in 75% region of the F gene(between 334-1682 nt), which is used to group NDV strains into different genotypes, were also analysed with the aid of computer program MegAlign, it is very interesting to find that the 4 strains showed a distinct distribution pattern from all the genotypes so far reported(genotype I-VIII), characterized by the simultaneously presence of a Bsto I site at 752 nt and two Rsa I sites at 872 nt and 973 nt. Additionally, 3 out of the 4 strains, despite their different geographical locations, showed a novel Rsa I site at position 1249 which is absent in all of the other genotypes. The 4 NDV strains of goose origin were essentially virulent ones, and probably belong to a new genotype.