【作者】 张伟；

【导师】 崔言顺；

【作者基本信息】 山东农业大学 ， 预防兽医学， 2014， 硕士

【摘要】 鸡传染性支气管炎(Infectious bronchitis，IB)是由禽传染性支气管炎病毒(Infectiousbronchitis virus，IBV)引起的鸡的一种急性，高度接触性传染病，目前，虽然IB弱毒活疫苗在鸡场广泛使用，但是IB并未得到有效控制，免疫失败现象时有发生，给养殖业带来了巨大经济损失。因此，开展IB流行病学研究以及评价疫苗株对流行株的免疫保护效果具有重要兽医指导意义。2011-2013年，在山东各地送检的133份病料中，共分离鉴定了48份IBV，我们选取了11株IBV，对其遗传变异情况展开研究。S1基因序列遗传进化分析发现，11株IBV中的10株是属于以QX为代表的基因I型，而剩余的1个毒株SDIB781/2012属于基因IV型，这表明以QX为代表的基因I型是山东省目前流行的优势基因型。基因I型的10株IBV流行株与QX为代表的参考株的核苷酸及推导氨基酸序列的同源性分别为91.7-96.3%和93.1-96.3%。而属于基因IV型的SDIB781/2012与10株IBV流行株的核苷酸及其推导的氨基酸序列的同源性均较低，分别为67.0-69.1%和59.1-61.3%。N基因序列分析发现，11株IBV分离株属于同一个基因群，其核苷酸及推导氨基酸序列的同源性分别为95.2-99.8%和92.9-99.5%；SDIB781/2012与QX为代表的参考株的核苷酸及推导的氨基酸序列的同源性分别为92.5%和93.4%。M基因序列分析发现，11株IBV分离株的核苷酸及推导氨基酸序列的同源性分别为95.3-100%和97.3-99.6%，而SDIB781/2012与QX为代表的参考株核苷酸及推导的氨基酸序列的同源性为91.3%和95.1%。这说明分离株SDIB781/2012在进化过程中发生了基因重组。本实验对部分山东IBV分离株的遗传进化进行了分析，发现11株山东IBV分离株分属于两个基因型：QX基因型和TC07-2基因型，而QX基因型是山东目前流行的优势基因型。分别选取了QX基因型和TC07-2基因型的代表毒株，对这两个不同基因型IBV的致病性进行了研究。结果发现，这两种基因型的IBV在发病时间、病程、病毒在鸡体内复制效率、Elisa抗体的产生等方面都存在差异。为了明确现有IB弱毒活疫苗对IBV优势流行基因型的免疫保护效力，本实验选取4种常用的IB弱毒活疫苗：491、2886、Ma5和H120，对其免疫保效果进行评价。免疫后14d，用流行株SDIB821/2012对试验组和对照组鸡群进行攻毒，结果表明：491免疫组保护率为90%，而2886、Ma5和H120对分离株几乎没有保护力。攻毒后3d、5d和7d各免疫组和对照组试验鸡气管、肺和肾脏组织病毒检出率没有明显差异，表明4种IB疫苗均不能有效阻止病毒在试验鸡气管、肺脏和肾脏组织内复制。进一步攻毒实验表明，IB病毒在免疫过491的鸡体内的复制效率最低，存在时间最短。更多还原

【Abstract】 Infectious Bronchitis (IB) is an acute, highly contagious chicken disease which is causedby IBV. Currently, IB has not been effectively controlled although the attenuated live vaccinesare widely used in farms., and immunity failure which occurs occasionally results in hugeeconomic losses to the breeding industry.So, it has important guiding significance to conductepidemiological research and evaluate the protective immunity of vaccine strains againstepidemic strainsDuring2011-2013,we isolated and identified48strains IBV from133pathologicalmaterials in Shandong province, we selected11strains to study their genetic variation.Genetic evolution analysis of S1gene sequence indicates that10strains belong to thegenotypeⅠwhich is represented by QX，and the other strain, SDIB781/2012,belongs togenotype Ⅳ.It indicates that the genotype Ⅰwhich is represented by QX is the circulationdominant genotype in Shandong Province in the moment. The nucleotide and deduced aminoacid sequence identities between10genotype I IBV pandemic strains and the reference strainwhich is represented by QX are91.7-96.3%and93.1-96.3%respectively. While thenucleotide and deduced amino acid sequence identities between SDIB781/2012belonging togenotype Ⅳand10IBV pandemic strains are low, which are67.0-69.1%and59.1-61.3%respectively. Analysis of N gene sequence suggests that11isolate strains of IBV belong tosame gene group,the nucleotide and deduced amino acid sequence identities are95.2-99.8%and92.9-99.5%respectively; the nucleotide and deduced amino acid sequence identitiesbetween SDIB781/2012and the reference strain which is represented by QX are92.5%and93.4%respectively. Analysis of M gene sequence indicates that the nucleotide and deducedamino acid sequence identities of11IBV isolate strains are95.3-100%and97.3-99.6%respectively;while, the nucleotide and deduced amino acid sequence identities betweenSDIB781/2012and the reference strain which is represented by QX are91.3%and95.1%,This indicates that genetic recombination occurred during evolution.In this experiment,we analyzed the genetic evolution of IBV isolate strains in ShandongProvince, finding that11strains IBV isolates belong to two genotypes:QX genotype andTC07-2genotype, and QX genotype was the popular dominant genotype in Shandong in themoment. We selected the representative strains of QX genotype and TC07-2genotype,and studied the pathogenicity of the two different genotypes. The result suggested that there weredifferences in both genotypes IBV in time of onset, duration, viral replication efficiency, andantibody production.In order to clarify the immune protective efficacy of existing IB live attenuated vaccineagainst IBV advantaged genotype,we selected4commonly used IB attenuated livevaccines:491,2886,Ma5and H120to evaluat the effect of the immune protection.14d afterimmunization, the test group and control group chicken were inoculated with the epidemicstrain of SDIB821/2012.The results indicates that protection efficiency of the group immunedwith491is90%, while the group immuned with2886,Ma5and H120almost have noprotection efficiency against isolates. The virus detection rates of immuned groups andcontrol groups have no significant difference in trachea, lungs and kidney. It suggests that the4kinds of IB vaccines cannot prevent virus replicate in trachea, lungs and kidney. Furtherexperiments showed that IBV virus in chickens immuned with491had a low replicationefficiency, and shortest time existence.更多还原