Search

To determine sequence characteristics and phylogenetic relationships of the nonstructural (NS) gene, the NS genes of 9 avian influenza (AI) viruses were sequenced and compared with other Iranian AI H9N2 viruses available in GenBank. The similarity among the earliest Iranian H9N2 isolate (A/chicken/Iran/ZMT-101/1998) and recent (2007-2011) studied isolates was low (94%). Some of the studied viruses revealed substitutions in RNA-binding and effector domains as well as antigenic regions of the NS protein. Recently studied isolates have a high similarity (97.4%-98.7%) with some Pakistani isolates (like A/chicken/Sawabi/NARC-2434/2006) in the NS gene. In the phylogenetic analysis, recently studied isolates composed a cluster separate from other Iranian isolates and were placed in the neighborhood of some Pakistani isolates. Hence, new Iranian H9N2 isolates may originate from Pakistani isolates. The NS protein of the Iranian H9N2 isolates differed from that of the Iranian highly pathogenic H5N1 viruses. The potential risk of the emergence of a pandemic virus because of the reassortment of the internal genes between H9N2 viruses and highly pathogenic AI viruses on one hand and the genetic and amino acid changes of AI viruses affecting their pathogenicity and immunogenicity on the other hand confirm the importance of continued surveillance of AI viruses. [ABSTRACT FROM AUTHOR]

Backgrounds and Objectives: Classified as low pathogenic avian influenza (LPAI) viruses, the H9N2 subtype causes severe respiratory disease in poultry farms and occasional respiratory disease in humans. In this study, the neuraminidase (NA) gene of three Avian Influenza (AI) H9N2 strains isolated from poultry farms in Iran during 2010-11, as well as other reported Iranian H9N2 isolates, were genetically analyzed and their nucleotide changes were evaluated. Materials and Methods: The NA gene of three AIVs were sequenced and evaluated for genetic characteristics and phylogenetic relationship. Results: One new potential glycosylation site (PGS) at amino acid position 306 was observed in one of the studied isolates (A/Chicken/Iran/N102/2011). Antigenic sites of NA in Iranian H9N2 isolates have varied in a yearly manner. The Iranian isolates can be divided into 2 main subgroups; 11-T like subgroup viruses isolated mainly during 1998-2004 and second subgroup viruses isolated during 2004-2009. Interestingly, the three studied isolates fell into a third subgroup. The nucleotide sequences of the three studied isolates showed high identity to recent Pakistani H9N2 isolates (94.5-97%) compared to former Iranian AIV isolates (89-94%). Conclusion: High frequency of substitutions in the NA gene of studied isolates in recent years and effects of those substitutions on the pathogenicity of AI virus highlight the need to continue surveillance of genetic characteristics of AIV H9N2 in Iran. [ABSTRACT FROM AUTHOR]