Ghalyanchi Langeroudi Arash, Karimi Vahid, Tavasoti Kheiri Masoumeh, Barin Abbas
1Department of Microbiology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
3Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Tehran, Tehran, P.O. Box 14155-6453, Iran.
Comp Clin Path. 2013;22(3):321-330. doi: 10.1007/s00580-012-1405-x. Epub 2012 Jan 21.
H9N2 avian influenza A viruses (AIV) have become panzootic in Eurasia over the last decade and are endemic in Iran since 1998, and inactivated vaccine has been used in chickens to control the disease. The hemagglutinin (HA), one of eight protein-coding genes, plays an important role during the early stage of infection. To study their evolution and zoonotic potential, we conducted an in silico analysis of H9N2 viruses that have infected broiler in Tehran Province, Iran between 1998 and 2007. The complete coding region of HA genes from nine H9N2 subtypes isolated from chicken flocks in Tehran Province during 1998-2007 was amplified and sequenced. Sequence analysis and phylogenetic studies of H9N2 subtype viruses on the basis of data of 9 viruses in this study and 30 selected strains are available in the GenBank. Sequence and phylogenetic analyses revealed a large number of similar substitution mutations and close evolutionary relation among sequences of HA. The isolates possessed two types of amino acid motif -R-S-S-R/G-L- and -R-S-N-R/G-L- at the cleavage site of HA. The results showed that all nine representative H9N2 isolates belong to low pathogenic AIVs since none of the amino acid sequences at the cleavage site of the HA of the isolates possessed the basic motif required for highly pathogenic viruses (R-X-R/K-R). Six out of these nine isolates possessed leucine at position 226, which prevails in the sequences found in human strains. Phylogenetic analysis showed that all our isolates belonged to the G1-like sublineage. Also, these isolates showed some degree of homology with other H9N2 isolates, e.g., 89.46-93.93.39% with qu/HK/G1/97 and 93.39-98.39% with pa/Narita/92A/98. The available evidence indicates that HA genes of H9 influenza virus circulating in Iran during the past years were not well conserved. Our finding emphasizes the importance of reinforcing AIV surveillance, especially after the emergence of high pathogenicity in poultry in Iran.
在过去十年中，H9N2甲型禽流感病毒（AIV）在欧亚大陆广泛传播，自1998年起在伊朗呈地方流行状态，并且已使用灭活疫苗来控制鸡群中的该疾病。血凝素（HA）是八个蛋白质编码基因之一，在感染早期起着重要作用。为了研究其进化和人畜共患病潜力，我们对1998年至2007年间在伊朗德黑兰省感染肉鸡的H9N2病毒进行了计算机分析。扩增并测序了1998 - 2007年间从德黑兰省鸡群中分离出的9种H9N2亚型HA基因的完整编码区。基于本研究中的9种病毒和GenBank中选定的30个菌株的数据，对H9N2亚型病毒进行了序列分析和系统发育研究。序列和系统发育分析揭示了HA序列之间大量相似的替代突变和密切的进化关系。分离株在HA的裂解位点具有两种氨基酸基序 -R-S-S-R/G-L- 和 -R-S-N-R/G-L-。结果表明，所有九个代表性H9N2分离株均属于低致病性AIV，因为分离株HA裂解位点的氨基酸序列均不具有高致病性病毒所需的基本基序（R-X-R/K-R）。这九个分离株中有六个在第226位具有亮氨酸，这在人类菌株的序列中占主导地位。系统发育分析表明，我们所有的分离株都属于G1样亚系。此外，这些分离株与其他H9N2分离株表现出一定程度的同源性，例如，与qu/HK/G1/97的同源性为89.46 - 93.93%，与pa/Narita/92A/98的同源性为93.39 - 98.39%。现有证据表明，过去几年在伊朗流行的H9流感病毒的HA基因保存不佳。我们的发现强调了加强AIV监测的重要性，特别是在伊朗家禽中出现高致病性之后。
