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1.
Sixteen infectious bronchitis virus (IBV) isolates were recovered from broilers and layers from five geographic poultry regions in Colombia. The viruses were isolated from tracheas, lungs, and cecal tonsils of birds, previously vaccinated with the Massachusetts strain, that were showing respiratory signs. Further analysis of the IBV isolates was achieved by phylogenetic analysis comparing their deduced amino acid sequences in the hypervariable region 1 of the S1 gene with reference strains. Four unique genotype clusters containing isolates with indigenous genotypes were observed. One isolate was found to be the Connecticut genotype and three isolates were found to be the Massachusetts genotype.  相似文献   

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Thirty-three field isolates of avian infectious bronchitis virus (IBV) were recovered from commercial chicken flocks in Korea between 2003 and 2006 and were characterized phylogenetically by nucleotide sequence analysis of the IBV S1 gene hyper-variable region. Our phylogenetic analysis revealed that recent field isolates of IBV formed at least three distinct phylogenetic types, including K-I, K-II, and K-III. K-I type IBV consisted of indigenous, 13 IBV isolates which evolved from the Kr-EJ/95 strain and then separated into the lineages of type K-Ia and type K-Ib. K-II type IBV isolates (n = 19) were closely related to nephropathogenic IBV variants from China and Japan. The K-III type isolate (Kr/D064/05), first identified by this study, was closely related to enteric IBV variants from the Chinese strains that cause proventriculitis. Sequence comparisons showed amino acid differences of >27.5% between IBV types. The molecular epidemiologic characteristics of IBV field isolates are briefly discussed.  相似文献   

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Infectious bronchitis virus (IBV) causes avian infectious bronchitis, an important disease that produces severe economic losses in the poultry industry worldwide. Recent IBV infections in Sweden have been associated with poor growth in broilers, drop in egg production and thin egg shells in layers. The complete spike gene of selected isolates from IBV cases was amplified and sequenced using conventional RT-PCR. Nucleotide and amino acid sequence comparisons have shown that the recent isolates bear 98.97% genetic similarity with strains of the QX-like genotype. The phylogenetic analysis revealed that strains predominant in the nineties, which were of the Massachusetts type, have been replaced by D388/QX-like strains, however the evolutionary link could not be established. The homology between the two genotypes was 79 and 81%. Remarkably, a strong positive selection pressure was determined, mostly involving the S1 subunit of the S gene. This strong selective pressure resulted in recombination events, insertions and deletions in the S gene. Two new isolates generated from recombination were found with nucleotide sequence diverging 1.7-2.4% from the D388/QX-like branch, indicating the emergence of a new lineage. The study demonstrates a constant evolution of IBV that might be in relation to increased poultry farming, trade and vaccine pressure. The findings underscore the importance of continuous monitoring to control spread of infections, as well as to timely adjust diagnostic methods, molecular epidemiological studies, development and use of vaccines that are adapted to the changing disease scenario.  相似文献   

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Xu C  Zhao J  Hu X  Zhang G 《Veterinary microbiology》2007,122(1-2):61-71
Between 2003 and 2005, four strains of infectious bronchitis virus (IBV) were isolated from the vaccinated chicken flocks in China. The results from chicken embryo cross-neutralization assays showed that all the four isolates were relative to strain A2 of IBV, which was isolated in 1996 in Beijing and related to strain 4/91. The S1 gene of the spike protein was amplified and sequenced. The nucleotide and amino acid sequence of the S1 gene had a similar degree of identity (88.98-99.28%) among the four Chinese IBV isolates. The identity of the S1 protein gene between the four Chinese IBV isolates and 14 strains of other IBVs varied from 70.06 to 81.59%. Phylogenetic analysis suggested that there are at least four groups of IBVs circulating in China and the disease outbreaks might have been caused by infection of multiple strains of IBV.  相似文献   

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采用RT-PCR方法,以IBVS1全基因特异性引物分别从我国华东(HD)、华北(HB)、华中(HZ)、华南(HN)、西北(XB)及东北(DB)等地的IBV流行株基因组中扩增出预期的1.7kb左右的DNA片段。PCR产物的HaeII酶切分析及其与英国IBVS1全基因核酸探针的分子杂交证实所获6个IBV流行株的PCR产物为IBVS1基因。将此6个毒株的S1基因PCR产物分别进行5’和3’端的BamHI和HindII酶切识别位点的分子修饰之后插入到克隆质粒pUC18的BamHI/HindII位点,在大肠杆菌中实现了目的基因的分子克隆。S1基因的RFLP分析表明我国IBV已有分子水平的变异。  相似文献   

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Nephropathogenic infectious bronchitis (NIB) was diagnosed in 28 infectious bronchitis virus (IBV)-vaccinated commercial chicken flocks in Pennsylvania from December 1997 to July 2000. Early dinical signs were increased flock mortality and urinary water loss (polyuria and pollakiuria) leading to wet litter. Daily mortality ranged from 0.01% in layers to 2.45% in broilers, with total broiler mortality as high as 23%. Severe renal swelling and accumulation of urates in the tubules were commonly seen. Visceral gout and urolithiasis were less frequently observed. Histopathologic changes included characteristic tubular epithelial degeneration and sloughing with lymphoplasmacytic interstitial nephritis. Minimal respiratory disease signs were noted in broilers. Egg production and shell quality declined in layers. Confirmatory diagnosis of NIB was made by IBV antigen-specific immunohistochemical staining of the renal tubular epithelium and virus isolation. Sequencing of the S1 subunit gene of 21 IBV isolates showed the NIB outbreak to be associated with two unique genotypes, PA/Wolgemuth/98 and PA/171/99. The cases from which the genotypes were isolated were clinically indistinguishable. The NIB viruses were unrelated to previously recognized endemic strains in Pennsylvania and were also dissimilar to each other. Genotype PA/Wolgemuth/98 was isolated almost exclusively during the first 14 mo of the outbreak, whereas PA/171/99 was recovered during the final 18 mo. The reason for the apparent replacement of PA/Wolgemuth/98 by PA/171/99 is not known.  相似文献   

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Thirteen field isolates of infectious bronchitis virus (IBV) were isolated from broiler flocks in Thailand between January and June 2008. The 878-bp of the S1 gene covering a hypervariable region was amplified and sequenced. Phylogenetic analysis based on that region revealed that these viruses were separated into two groups (I and II). IBV isolates in group I were not related to other IBV strains published in the GenBank database. Group 1 nucleotide sequence identities were less than 85% and amino acid sequence identities less than 84% in common with IBVs published in the GenBank database. This group likely represents the strains indigenous to Thailand. The isolates in group II showed a close relationship with Chinese IBVs. They had nucleotide sequence identities of 97-98% and amino acid sequence identities 96-98% in common with Chinese IBVs (strain A2, SH and QXIBV). This finding indicated that the recent Thai IBVs evolved separately and at least two groups of viruses are circulating in Thailand.  相似文献   

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从山东省发病鸡群中分离鉴定了一株鸡传染性支气管炎病毒(Infectious bronchitis virus,IBV)强毒株SDIB821/2012,对其进行S1基因序列测定分析和免疫保护试验。S1基因遗传进化分析结果显示,SDIB821/2012属于以QXIBV为代表的基因型,与同属一个基因型的IBV参考株氨基酸同源性为91.6%~98.5%,与疫苗株491同源性为77.6%,与H120和MA5同源性均为74.8%。免疫保护试验结果显示,根据试验鸡临床症状和发病死亡情况,弱毒活疫苗491对SDIB821/2012的保护率为90%,而H120和MA5对SDIB821/2012的保护率分别仅为40%和33%。攻毒后各免疫组喉头、泄殖腔棉拭样品以及气管、肺脏和肾脏组织均可检测到病毒,表明3种IB疫苗均不能对SDIB821/2012提供完全的免疫保护。  相似文献   

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试验旨在确定国内鸡肾型传染性支气管炎病毒(IBV)流行毒株核蛋白N与市场上现用疫苗株、近年国内外分离株的差异性.本研究利用自山东某鸡场病鸡肾脏组织分离获得、经PCR鉴定为IBV阳性的毒株(命名为SD03株),参考NCBI上部分IBV毒株N基因的保守区域设计引物,进行RT-PCR扩增,构建重组pMD18-T-N/DH5α菌,测序获得N基因序列.与参考株进行了核苷酸及氨基酸同源性分析,结合DNAStar软件与http://www.expasy.org/网站对该基因编码的蛋白进行理化性质分析.结果显示,SD03株为IBV肾型毒株,与LDT3、partridge/GD/S14/2003毒株(肾型)核苷酸及氨基酸同源性均在99.0%以上.与其他国内外肾型经典毒株Ma5、W93、Gray、Holte株氨基酸同源性为90.0%~94.6%,与国内外呼吸型疫苗株H120、H52、M41氨基酸同源性为89.7%~91.0%.本研究深入分析了当前流行株SD03株N蛋白的理化特性,为N蛋白亚单位疫苗在不同系统中表达及蛋白纯化提供了理论依据,为中国现阶段IBV的防控奠定了一定的理论基础.  相似文献   

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本研究对分离自沈阳地区的一株传染性支气管炎病毒(SY毒株)进行了生物学特性的研究,同时成功地对其免疫原S1基因进行了RT-PCR扩增、克隆与序列分析。 通过电镜观察、动物回归试验、血凝特性研究等试验验证分离自沈阳地区的SY毒株确实为一株传染性支气管炎病毒。气管环组织培养交叉中和试验结果表明,分离株SY株不同于参考毒株澳大利亚T、H52、M41,且不同于国内其它流行株HD、HB、XB、DB等,是一个新的变异株。 利用IBV S1基因特异性寡聚核苷酸引物,经RT-PCR扩增SY毒株的S1基因,得到预期的约1.7Kb片段;并将扩增所得cDNA插入克隆质粒pUC19的EcoRⅠ/BamHⅠ位点,在大肠杆菌DH5a中实现目的基因的克隆。经限制性核酸内切酶分析及PCR鉴定,证实为阳性重组质粒,利用末端双脱氧链终止法对其测序,得到S1基因全长1640bp,包括整个开放阅读框。通过序列分析软件DNASIS、PROSIS、MEGA等软件对S1基因核苷酸序列及推导的氨基酸序列进行分析,结果表明:分离株SY与7株参考株和国内流行株HD株相比,无论是核苷酸序列同源百分率还是氨基酸序列同源百分离都较低,均未达到80%,这就提示我们SY毒  相似文献   

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采用RT—PCR方法对近年来本实验室分离的4株肾型IBV陕西分离株的纤突蛋白S1基因、膜蛋白基因(M)和核蛋白基因(N)分别进行扩增,测序后进行遗传变异分析。结果显示:与肾型疫苗株w93相比,各分离株S1基因均存在广泛的点突变,并且都存在基因插入现象,分离株之间氨基酸同源性为75.8%~99.4%;M基因除了存在点突变外,W09和WNl2在其5’端还存在9个核苷酸的缺失,分离株之间氨基酸同源性为91.0%~99.6%;N基N无插入和缺失,但存在基因点突变,分离株之间氨基酸同源性为99.3%~99.5%。4株IBV分离株在S1、M和N基因氨基酸系统进化树上分属于不同的进化群,且都与较早的肾型IBV陕西分离株w118遗传距离较远。结果表明,4株鸡肾型IBV流行毒株的s1、M和N基因均存在不同程度变异,这可能是免疫鸡群肾型鸡传染性支气管炎长期流行的主要原因.  相似文献   

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Avian infectious bronchitis virus (IBV) causes tremendous economic losses to the poultry industry worldwide. Different serotypes of this virus show little cross-protection. The present study investigated the genotypic relationship between CK/CH/LDL/97I-type strains and reference IBVs based on S1 gene comparisons and the protection provided by vaccination with commercial vaccines and attenuated homologous and heterologous strains. Phylogenetic analysis and the comparison of S1 showed that CK/CH/LDL/97I-type virus might be a new serotype compared to vaccine strains and other types of IBV isolates in China. Protection efficacy was evaluated by morbidity, mortality, and virus re-isolation from the challenged chicks. Complete protection by IBV vaccination was provided by the homologous strain but sufficient respiratory protection was not provided by the commercial vaccines. Heterologous strains against CK/CH/LDL/97I challenge and the development of a vaccine against CK/CH/LDL/97I-type IBV will be necessary to control infectious bronchitis disease in poultry. Further development of the attenuated CK/CH/LDL/97I strain may provide a valuable contribution towards this goal.  相似文献   

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