Restriction fragment length polymorphism analysis of the F gene of Newcastle disease viruses isolated from chickens and an owl in Taiwan

To provide information on the epidemiology of Newcastle disease (ND) of pou ltry in Taiwan, ND virus isolates From chickens and an owl were investigate d by restriction site analysis and sequencing of their gene. A 1,349 base f ragment of the F (fusion protein) gene was amplified by reverse transcripti on-polymerase chain reaction (RT-PCR). The PCR products were analyzed using restriction endonucleases, HinfI, BstOI, and RsaI. Three strains isolated from chickens during the 1995 epidemic outbreak had the same restriction si tes as that of a 1994 isolate; the number of the restriction sites of HinfI , BstOI, and RsaI were 4, 2, and 4, respectively. In the F gene of the stra in isolated from an owl during the same outbreak an additional restriction site of HinfI was found. The 1991 isolate had only 3 restriction sites. The F gene of the owl isolate was amplified by RT-PCR and followed by direct s equencing. The deduced amino acid sequence at the cleavage site of the F pr otein was of virulent strains, R-112-R-Q-K-R-F-117, The F gene of Ow/Tw/220 9/95 was phylogenetically most closely related to that of Ck/Tw/2137/95 iso lated from the same outbreak. The present results indicate that the causati ve virus of the 1995 ND outbreak had already been present in Taiwan.