Analysis of the Amino Acid Sequence of Fo Cleavage Site at

• Main Authors: Lin, Yeou-Liang, 林有良
• Other Authors: Happy K. Shieh
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/10439273994244813270

碩士 === 國立中興大學 === 獸醫微生物學研究所 === 85 === There were three major outbreaks of Newcastle disease in Taiwan. Sixteen Taiwanese isolates from these outbreaks, together with 5 vaccine strains, 3 Saudi Arabian isolates and the Sato strain, were subject to RT-PCR (reverse transcription- polymerase chain reaction) amplification and direct DNA sequencing. The sequences obtained were then compiled by GCG software and analyzed by PAUP (phylogenetic analysis using parsimony) to construct the phylogenetic tree of these viruses. The tree was found to contain six main groups. The first three groups are composed of Taiwanese isolates in three different groups exhibited extensive sequence variations, which might be due to the accumulation of mutations during the replication of RNA viruses. Moreover, amino-acid sequences predicted from the nucleotide sequences by the GCG software revealed that all Taiwanese isolates, except one, have two pairs of basic amino acids in their F0 cleavage site. In addition, the residue in the position 117 of F0 protein fromall Taiwanese isolates was found to be phenylalanine, indicating that all these isolates are virulent viruses. For the vaccine strains analyzed, the residue in the position 117 was leucine, the overall sequences revealed that they are avirulent strains. Finally, three Saudi Arabian isolates, and the Sato strain all showed typical amino- acid sequences of virulent viruses.