Avian influenza viruses of the H9N2 subtype have seriously affected the industry of the Middle East and Asian countries since the 1990s and are considered to be one of the potential candidates for the next human pandemic. In the present study, to determine the genetic relationship of Iranian viruses, the haemagglutinin (HA) genes from two isolates of H9N2 viruses from commercial chickens in Markazi province (central Iran) during 2013– 2014 were amplified and sequenced. Samples were collected and viruses were passed in embryonated hen eggs and virion RNA was extracted from allantoic fluid and reverse transcribed to synthesise cDNA. cDNA was amplified by PCR and the PCR product was purified with a purification kit. Purified fragments were sequenced from both directions. Finally, sequence analysis and phylogenetic studies were conducted by comparing each isolate with those of the available H9N2 strains at Gen Bank. All of the isolates possessed the same amino acid motif P-A-R-S-S-R/G-L at the HA cleavage site. Amino acid sequence comparisons of HA genes of two isolates showed 93.6% identity. Phylogenetic analysis revealed that all isolates belonged to the G1-like sublineage and one isolate showed some degree of homology with Pakistani isolates. Two isolates had leucine (L) at position 226 instead of glutamine (Q) which indicated the potential of binding to human-type receptors. The results of this study suggest that Iranian H9N2 viruses could infect mammalian species, including humans and have the potential to emerge as highly pathogenic influenza viruses in Iran.

中文翻译：

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伊朗Markazi省商品鸡H9N2禽流感病毒血凝素基因序列及系统发育分析

自1990年代以来，H9N2亚型禽流感病毒严重影响了中东和亚洲国家的工业，被认为是下一次人类大流行的潜在候选病毒之一。在本研究中，为了确定伊朗病毒的遗传关系，对 2013 年至 2014 年间来自马尔卡齐省（伊朗中部）商品鸡的两个 H9N2 病毒分离株的血凝素 (HA) 基因进行了扩增和测序。收集样品并将病毒传给含胚鸡蛋，从尿囊液中提取病毒粒子 RNA 并逆转录以合成 cDNA。PCR扩增cDNA，PCR产物用纯化试剂盒纯化。从两个方向对纯化的片段进行测序。最后，通过将每个分离株与 Gen Bank 中可用的 H9N2 菌株进行比较，进行序列分析和系统发育研究。所有分离株在 HA 切割位点都具有相同的氨基酸基序 PARSSR/GL。两个分离株的 HA 基因的氨基酸序列比较显示 93.6% 的同一性。系统发育分析表明，所有分离株都属于 G1 样亚谱系，其中一个分离株与巴基斯坦分离株有一定程度的同源性。两个分离株在 226 位具有亮氨酸 (L) 而不是谷氨酰胺 (Q)，这表明与人类型受体结合的潜力。这项研究的结果表明，伊朗 H9N2 病毒可以感染包括人类在内的哺乳动物物种，并有可能在伊朗成为高致病性流感病毒。