[Characterization and phylogenetic analysis of neuraminidase gene in isolated Avian Influenza viruses of H[9]N[2] subtype from Iran]

Avian Influenza [AI] is a rival respiratory disease of poultry industry that cause great economic losses in worldwide. In this study, the neuraminidase [NA] gene of two H[9]N[2] avian influenza virus [AIV] strains [A/Chicken/Iran/ZMT-101 / 1998 and A/Chicken/Iran/NGV-1/2006], isolated from AI infected poultry farms in 1998 and 2006, were cloned and sequenced. Amino acids at hemadsorbing [HB] site of these isolates showed some differences between them and also with other Iranian isolates. No insertion or deletion or shortening in the stalk region of the NA gene were observed. Phylogenetic analysis showed that N[2] gene of these strains, belonged to the same A/Qail/Hong Kong/ G1/ 97-like virus sublineage. However, these strains were allocated in two different groups in the same sublineage. These results indicate that N2 gene and protein sequences of the recently isolated H[9]N[2] stain [NG-1/2006] have substantial variation compared to the previous Iranian reported H[9]N[2] strain [ZMT-101/1998]. These changes may cause some new biologic and immunologic characteristics for AIVs, such as reduction of vaccination efficacy in immunized chickens. Therefore, evaluation of important genes and protective efficacy of used H[9]N[2] vaccine strain used in Iran would be crucial

Comparison between RT-PCR and viral solation for detection OFH9 subtype of avian influenza viruses

During 2004-2006, a total number of 22 tissue samples obtained from poultry flocks suspected to respiratory diseases submitted to avian virology laboratory of faculty of veterinary medicine, were prepared for avian influenza virus [AIV] isolation in embryonated chicken eggs, according to the standard method. RT-PCR was established on tissue samples using specific primers for H9 gene. 3.5 Amplified PCR products were 435 bp in length. Analytical sensitivity of the RT-PCR was 10 EID50 and sensitivity, specificity and correlation rate compared with virus isolation, were 100%, 94% and 95%, respectively. The results showed that the RT-PCR assay using H9 gene specific primers, directly on tissue samples, could be used in rapid detection and subtyping of H9 AIVs as a useful alternative to virus isolation assay