【摘要】 为了解GI-19型（QX型）鸡传染性支气管炎病毒（infectious bronchitis virus,IBV）的病原特性,筛选6株GI-19型IBV进行EID₅₀测定以及鸡胚致病力和雏鸡致病性试验,并应用高通量测序技术进行基因组测序,分析病毒基因组和主要结构蛋白编码基因生物特性。结果显示:IBV/Chicken/Hubei/S1402/2021分离株对鸡胚有致病性,导致鸡胚表现胚体蜷缩、矮小等典型病变特征,经SPF鸡胚传代至第5代,表现较为稳定的EID50 (10^-5.33/0.1 mL),但其对雏鸡无致病性;IBV/Chicken/Sichuan/C1452/2021分离株对鸡胚没有致病性,但将其接种1日龄雏鸡,可导致雏鸡出现33.33%（5/15）的发病率,引起的典型病变为雏鸡肾脏尿酸盐沉积。对6株GI-19型IBV分离株的基因组和主要结构蛋白编码基因进行系统进化分析和生物特性分析,发现IBV/Chicken/Hubei/S1402/2021分离株与其他分离株存在明显差异,且在1a和1b基因区域存在重组现象。结果表明:我国流行的部分IBV毒株对鸡胚和雏鸡的致病性存在差异;IBV毒株S1基因的变异可能会影响其致病力,而N基因的变异可能会影响其感染细胞的能力。本研究分析了部分GI-19型IBV毒株的病原学特征,为揭示IBV的致病机理和免疫机制奠定了基础,为制定鸡传染性支气管炎防控策略提供了依据。更多还原

【Abstract】 In order to investigate the pathogenic characteristics of GI-19（QX） avian infectious bronchitis virus（IBV）,6 strains of GI-19 IBV were screened for EID₅₀ determination and tests of embryo virulence and chick pathogenicity,followed by genome sequencing using high-throughput sequencing to analyze the genetic biological characteristics of virus genome and major structural proteins.The results revealed that IB V/Chicken/Hubei/S1402/2021 isolate was pathogenic to chicken embryos,resulting in typical pathological changes including curled,short and small embryo bodies,EID₅₀(10^-5.33/0.1 mL) was stable after the isolate was passaged to the fifth generation via SPF chick embryos,but it was non-pathogenic to chicks;IB V/Chicken/Sichuan/C 1452/2021 isolate was non-pathogenic to chick embryos,but could lead to 33.33%（5/15） incidence in chicks when it was inoculated into 1-day-old chicks,causing the typical pathological changes of urate deposits in kidneys of chicks.It was found that,by phylogenetic analysis and biological characteristic analysis of the genome and main structural protein genes of 6 strains of GI-19 IBV isolates,IB V/Chicken/Hubei/S 1402/2021 isolate was significantly different from other isolates,and recombination was observed in.1a and 1b gene regions.In conclusion,the pathogenicity of some IBV isolates was different in chick embryos and chicks.The mutation of SI gene might affect its virulence,and that of N gene might affect its capacity to infect cells.In the study,the etiological characteristics of some GI-19 IBV violates were analyzed,which laid a foundation for researches on the pathogenesis and immune mechanism of IBV,and provided a reference for development of prevention and control strategies for avian infectious bronchitis（IB）.更多还原