Complete genome sequence and molecular characterization of thermostable Newcastle disease virus strain TS09-C

A thermostable avirulent Newcastle disease virus (NDV) strain TS09-C was developed by serial passage of V4 strain in BHK-21 cells. The complete genome sequence of strain TS09-C was determined and compared with the sequences of other NDV isolates representing different thermostable phenotypes. The TS09-C genome was 15,186 nucleotides long and consisted of eight genes in the order of 3′-NP-P/V/W-M-F-HN-L-5′. High levels of nucleotide and amino acid sequence identity existed among the thermostable NDV isolates. Thermostable strains TS09-C, V4, I-2, and Ulster all belonged to genotype I. The F protein cleavage site of strain TS09-C was 112 G- K -Q- R–R -L 117 , with an isolated basic amino acid and a pair of contiguous basic amino acids, differing from that of its parental V4 strain ( 112 G- K -Q-G- R -L 117 ). Our characterization of the complete genome of thermostable avirulent NDV strain TS09-C may facilitate the development of a thermostable NDV reverse genetic system and further study of the mechanism of thermostability of NDV.