不同年代的低致病性HH7N9亚型禽流感病毒对SPF鸡致病性的研究

Pathogenicity Comparison of Different Low Pathogenic H7N9 Subtype Avian Influenza Viruses Isolated from Different Years in Chickens

为了了解前4个流行波次中低致病性H7N9亚型禽流感病毒致病性的特点,选择2013~2016年不同年代的H7N9代表株进行了SPF鸡致病性试验,系统比较了各病毒在排毒、复制、诱导宿主免疫应答及引起鸡肺脏病理变化等方面的差异。致病性结果表明所有的鸡都没有明显的临床症状也未死亡。肺损伤及排毒结果显示,2016年分离的TZHY22引起的肺损伤最严重且其排毒能力最强、排毒持续时间长。病毒复制能力结果显示,2013年分离的TM24复制能力最强,能在多个脏器中(心、肝、脾、肺、肾、脑)高效复制。然而,2014年分离的JX148虽然复制能力和排毒能力都很弱,但其引起的细胞因子免疫应答最强烈,并对宿主脏器造成了一定的病理损伤。以上结果表明,不同年代的病毒在排毒、复制及致病力等方面各不相同,其强弱并没有随着年代的推移呈现规律性变化。研究为H7N9亚型禽流感病毒的致病机理研究和疫苗评价奠定了一定的基础。

In order to investigate the pathogenicity characteristics of the low virulence H7 N9 subtype avian influenza viruses from the former four epidemic waves, we systemically compared the virus replication, virus shedding, innate immune response and lung pathology in chickens induced by viruses from 2013 to 2016. The results showed that no death and no clinical signs were found in all virus-infected birds. Specifically, lung injury was most severe in 2016 isolate TZHY22-infected chickens. In addition, TZHY22 also shedding more efficiently than other virus as demonstrated by higher virus titers and longer time. When comparing virus replication, surprisingly, the 2013 isolate TM24 replicated most efficiently and could disseminate to multiple organs, including heart, liver, spleen, kidney and brain. However,although 2014 isolate JX148 virus replicated and shedding weakly, it triggered the strongest cytokine responses and could lead lung damage of the infected birds. Therefore, viruses from different years showed great discrepancy in pathogenicity and no obvious regular changes were observed as the years went on. The study further shed lights on the pathogenesis and vaccine evaluation of the H7 N9 subtype avian influenza virus.