Abstract: This experimental application one-step RT-PCR and fluorescence RT-PCR methods separate to a Newcastle disease virus, and the strain F gene was cloned, sequenced and analyzed, and found that F protein amino acid sequence at the cleavage site was 112Arg-Arg-Gln-Lys-Arg-Phe117 which was the same as virulent Newcastle disease virus.The result proved the strain was virulent Newcastle disease virus from the molecular level. Combined with F gene sequence of other reference strains of Newcastle disease in GenBank revealed that the strain with the current virulent virus Taiwan/95, SKY/03, SGM/01 had the same amino acid sequence exactly of the F gene cleavage site, but the traditional vaccine strain La Sota was different.

Key words: Newcastle disease; reverse transcriptase-polymerase chain reaction; fusion protein; virulent virus