تارا ممدی

Newcastle disease is an extr-emely contagious disease that infects many species of birds. Newcastle Disease Virus (NDV) belongs to the paramyxoviridae fa-mily and genus Rubulavirus. The mem-brane of the virus particle contains HN and F glycoproteins. Cleavage of the F glycop-rotein has a direct relation with the patog-enicity of the virus. The aim of this study was to determine the gene and protein sequences of F glycoprotein in virus strains isolated from recent outbreaks in Iran.

Six NDV Viruses were passaged and their RNA isolated. Using RT- PCR technique، cDNA prepar-ation and amplification of the gene were done. Isolates were assessed by electropho-resis and observed with UV. The isolates were digested with restriction enzyme Pst I. Finally، in order to corroborate the ampl-ified PCR product، DNA of isolates were purified، dried and sequenced.

In this study all of the NDV strains contained a 935 bp band that after digestion with Pst I، produce two bonds 720 bp and 180 bp. Nucleotide analysis showed single base mutations but that was not significant amino acid sequence and anal-ysis indicated no amino acid change in the cleavage site of F protein. Discussion &

Absence of point mutations in the cleavage site of F protein illustrated the importance of the maintained cleavage site of protein F among the strains studied.