امیر محمدحسین نیا دواتگر

Influenza viruses cause a variety of infections from high to low pathogenicity in hosts. Influenza virus Ais divided into subtypes based on two surface glycoproteins: the hemagglutinin (H) and the neuraminidase (N). Avian flu viruses do not normally infect humans, although, some sporadic human infections have been reported. The aim of this study was to identify and sequence the neuraminidase gene of Avian Influenza (AI) H9N2 virus isolated from recent outbreaks in Iran and comparative analyzing it with strains from other countries. Influenza viruses were passaged in embryonated eggs, and RNA extracted by RNX. TM kit. Using RT- PCR technique, cDNA preparation and amplification of N gene were done. The product was then assessed by electrophoresis and observed with UV, purified and sequenced. Neuraminidase gene nucleotide sequence from six isolates from different parts of Iran were identified and recorded at the GenBank. Comparative analysis with reference strains carried out for these sequences. No mutation had been observed in cytoplasmic domain, however, four mutations had been occurred at transmembrane domain, which two of them were silent and two were actually substitution of hydrophobic amino acids with similar ones. Nucleotide and amino acid analysis for the neuraminidase gene of H9N2 influenza virus of isolates obtained from different parts of Iran revealed similarities to other strains described from neighboring countries, such as Pakistan and Saudi Arabia. It seems like that they have common source with the same lineages.

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.