鸡传染性支气管炎病毒免疫机制和免疫预防研究进展

由鸡传染性支气管炎病毒（Infectious bronchitis virus,IBV）引起的鸡传染性支气管炎（Infectious bronchitis,IB）是高度传染的全球性鸡病之一,严重危害养鸡业。IBV众多的血清型及其基因组的不断变异,给IB的免疫防控带来很大的困难。IBV主要侵害鸡的呼吸系统、泌尿生殖系统和消化系统,病鸡出现呼吸困难、产蛋下降、肾炎和腺胃炎等症状和病变。IBV的特点是变异频繁,血清型复杂,所致疾病的临床表现差异很大。因此,IB已成为养禽业最难控制的疫病之一。鸡对IBV的免疫机制是国内外研究的热点之一。传统疫苗已不能完全保护免疫鸡群,开发IBV基因工程疫苗,从主要免疫原性蛋白的良好表达到免疫策略的不断完善,已成为未来预防IB的趋势。     

鸡传染性支气管炎油佐剂灭活疫苗免疫效果

80年代以来,鸡传染性支气管炎(IB)在我国流行日趋严重,给养鸡业造成了巨大经济损失,其主要原因是传染性支气管炎病毒(IBV)易发生变异,形成了许多不同血清型IBV变异株,由于不同血清型毒株间交叉保护力弱或根本无保护力,因而导致了免疫失败.     

鸡传染性支气管炎的免疫机制

由鸡传染性支气管炎病毒(Infectiousbronchitisvirus, IBV) 引起的鸡传染性支气管炎由于病毒血清型较多, 易于发生变异而难以免疫预防,成为养鸡业发展的重大阻力。本文从IBV的分子免疫学结构, 在鸡体内引起的体液免疫和细胞免疫方面进行IB免疫机制分析, 提出了具有借鉴价值的免疫方法。     

鸡传染性支气管炎病毒分子变异机制的研究

鸡传染性支气管炎(IB)目前已成为养鸡业中危害最大的病毒性传染病之一。病毒基因组RNA的点突变、缺失、插入和不同毒株基因组间的同源重组所导致的病毒血清型、基因型和组织嗜性的改变是造成现用疫苗免疫失败的主要原因。病毒的变异已成为当前对IBV病原学及本病免疫防制研究中的热点，作者重点就IBV变异机制及其变异株的来源等方面作一综述。     

我国禽传染性支气管炎病毒分子流行病学研究进展

禽传染性支气管炎（Infectious bronchitis,IB）是由禽传染性支气管炎病毒（Infectious bronchitis virus,IBV）引起的雏鸡和成年鸡呼吸系统以及泌尿生殖道组织损伤和病变的急性、高度接触性疾病。虽然临床上广泛使用疫苗免疫防控该病,但由于IBV基因组存在频繁的变异和重组,导致新基因型和血清型不断出现,从而造成我国鸡IB未能得到有效控制。文章详细介绍了基于IBV S1基因系统发育学建立的分型方法以及我国流行的IBV 4个基因型、18个分支的来源、传播和流行现状,为IB防控和疫苗研发提供参考。     

鸡传染性支气管炎研究进展

鸡传染性支气管炎(IB)是由传染性支气管炎病毒(IBV)引起的一种高度接触性传染病。IBV可引起鸡呼吸道、肾脏和生殖道等部位病变,并造成死亡,给养鸡业造成巨大的经济损失。由于不同基因型的IBV在组织嗜性和致病性方面有着较大的差异,且不同血清型/基因型之间交叉保护性低,因此,新IBV血清型/基因型的不断出现给本病的防控带来困难。论文综述了鸡传染性支气管炎病原学、流行与分布、分子遗传变异机制、IBV诱导的天然免疫应答、体外培养、诊断技术和防控措施等的研究进展,旨在为IB的相关研究提供理论依据和防控策略。     

鸡传染性支气管炎病毒分子生物学研究进展(上)

鸡传染性支气管炎(Infections Bronchitis of chickens缩写为IB)是鸡的一种急性、高度接触性呼吸道和泌尿生殖道传染病.临诊上以气管罗音、咳嗽和打喷嚏为主要特征,幼鸡感染可致死亡,产蛋鸡群感染则导致蛋的产量和质量下降.主要侵害鸡的呼吸系统、泌尿系统、消化系统、生殖系统.传染性支气管炎病毒(IBV)属冠状病毒科,其血清型极为复杂,目前已知IBV有30多个血清型,不同血清型及变异株间抗原性差异很大,且不断变异,这就给IBV的诊断、免疫及IBV血清型分型带来很大的困难.该病对养鸡业危害极大,从而引起了国内外禽病工作者的高度重视.分子生物学研究进展(上).     

鸡传染性支气管炎血清学等诊断技术的应用

鸡传染性支气管炎(IB)是由鸡传染性支气管炎病毒(IBV)引起的鸡的急性、高度接触性传染病，该病是以损伤气管、引起肾脏病变、母鸡产蛋量下降和产畸形蛋为特征。尤其是近年来由于IBV新的血清型不断增加和变异株的不断出现，给养鸡业造成了严重的经济损失。虽然IB疫苗的应用在一定程度上控制了本病的暴发和流行，但由于IBV血清型众多及地域之间的差异、各血清型之间的交叉保护性较     

肉仔鸡肾型传染性支气管炎的诊治研究

鸡传染性支气管炎是由传染性支气管炎病毒（IBV）引起的危害养鸡业的重要传染病之一。该病的特点是病情复杂,血清型众多,又具有高度传染性,鸡群同时感染不同毒株或使用弱毒疫苗发生基因重组而不断变异,使IBV侵害鸡体的靶器官也发生了变化。IgnjatovicJ等用澳大利亚分离的25株IBV人工感染SPF鸡,比较了其致病性,发现12株肾致病型IBV,10株呼吸型IBV,3株混合致病型IBV,侵害肺、肾。为有效防制本病,我们对其病原进行了分离与鉴定。     

鸡传染性支气管炎病毒的分子生物学研究进展

鸡传染性支气管炎(IB)是由冠状病毒属的冠状病毒引起的高度接触性传染病.是严重危害我国乃至世界养鸡业的重要疾病之一.鸡传染性支气管炎病毒(IBV)具有多血清型和多组织噬性,掌握IBV的分子生物学特点,对揭示IBV的致病机理和分子变异机制以有效防制IB具有重要意义,所以IBV的分子生物学研究成为热点,进展较快.     

I群禽腺病毒12个血清型毒株Hexon蛋白全基因序列测定和酶切位点分析

利用3对引物（A、B、C）分别进行I群禽腺病毒的12个血清型毒株的Hexon全基因序列PCR扩增,并进行序列测定和PCR—RFLP分析,通过DNAStar软件和MEGA软件进行序列分析并绘制遗传发育进化树。结果显示,Hexon基因全长为2800左右个核苷酸,编码约940个氨基酸,不同血清型之间的同源性为75．2％～99．5％,变异范围是0．0％～24．3％。推导的氨基酸同源性为20．7％～98．8％,差异性为0．0％～24．2％。12个血清型之间Hexon全基因序列信息用来评价I群禽腺病毒家族的种系发育关系,构建的进化树显示出5个主要的分支。选用限制性内切酶HaeⅡ,利用存在差异的Hexon序列片段D特异性可以有效区分大部分血清型。结果表明,获得了I群禽腺病毒12个血清型不同毒株的Hexon全基因序列并进行了分子进化分析,同时结合12个血清型PCR—RFLP分析,为进一步分析鉴别I群禽腺病毒不同血清型提供依据。     

Ⅰ群禽腺病毒12个血清型毒株Hexon蛋白全基因序列测定和酶切位点分析

利用3对引物(A、B、C)分别进行Ⅰ群禽腺病毒的12个血清型毒株的Hexon全基因序列PCR扩增,并进行序列测定和PCR-RFLP分析,通过DNAStar软件和MEGA软件进行序列分析并绘制遗传发育进化树。结果显示,Hexon基因全长为2 800左右个核苷酸,编码约940个氨基酸,不同血清型之间的同源性为75.2%～99.5%,变异范围是0.0%～24.3%。推导的氨基酸同源性为20.7%～98.8%,差异性为0.0%～24.2%。12个血清型之间Hexon全基因序列信息用来评价Ⅰ群禽腺病毒家族的种系发育关系,构建的进化树显示出5个主要的分支。选用限制性内切酶HaeⅡ,利用存在差异的Hexon序列片段D特异性可以有效区分大部分血清型。结果表明,获得了Ⅰ群禽腺病毒12个血清型不同毒株的Hexon全基因序列并进行了分子进化分析,同时结合12个血清型PCR-RFLP分析,为进一步分析鉴别Ⅰ群禽腺病毒不同血清型提供依据。     

The genetic organisation of the capsule biosynthesis region of Actinobacillus pleuropneumoniae serotypes 1, 6, 7, and 12

The aim of the present study was to investigate the organisation of the genes (cps) involved in biosynthesis the capsular polysaccharide (CPS) of Actinobacillus pleuropneumoniae serotypes 6, 7, and 12 and to compare these to the corresponding genes previously described in other A. pleuropneumoniae serotypes. In serotypes 6 and 7 the sequenced DNA regions comprised five and four open reading frames, respectively, designated cps6ABCDE and cps7ABCD, whereas the sequenced DNA region in serotype 12 comprised only two open reading frames designated cps12AB. At the amino acid level, CpsA, CpsB, and CpsC of A. pleuropneumoniae serotypes 2, 6, 7, and 8 contained a high degree of homology. At the amino acid level Cps6D revealed a high degree of homology to Cps8D, whereas Cps7D contained a high degree of homology to the Cps2D. The deduced gene product of the partially sequenced cps6E gene showed no homology to any deduced gene products of any cps genes of A. pleuropneumoniae investigated so far. None of the deduced gene products of the cps genes involved in encapsulation of A. pleuropneumoniae serotypes 2, 6, 7, and 8 revealed homology to the deduced gene products of the cps genes of serotypes 1, 5A, and 12. For some genes, a local homology was found to genes probably involved in teichoic acid synthesis in other bacteria. The results obtained revealed a high degree of homology among the genes involved in CPS biosynthesis for serotypes 2, 6, 7, and 8 and a different group of homologous cps genes for serotypes 1 and 12. In some serotype 7 strains, including the serotype 7 reference strain, WF83, the cps genes were not located adjacent to the genes responsible for CPS export (cpx), probably due to genetic rearrangements.     

广东屠猪肉样品中大肠杆菌耐药性与毒力特征的分析

为分析广东地区屠猪肉中大肠杆菌(E.coli)药物敏感菌株的血清型、毒力基因和系统进化背景,本研究从屠猪肉样品中分离出112株E.coli,采用玻片凝集法鉴定血清型,琼脂稀释法测定10种抗菌药的敏感性,PCR方法检测7种毒力相关基因,多重PCR方法进行系统进化背景判定。结果显示,112株E.coli中,定型菌株95株,分别属于15种血清型,其中O65、O131、O8和O158为优势血清型。几乎所有菌株对氟苯尼考、多西环素和四环素高度耐药,而对头孢曲松高度敏感,其中多重耐药菌株多数耐5种以上药物,常见的多重耐药表型是氟苯尼考/氯霉素/多西环素/四环素/氨苄西林。PCR鉴定结果表明,含有毒力基因的菌株中38%至少具有两个毒力基因,其中EAST1+Stx2e和hlyF+Stx2e比较常见。比较常见的毒力基因为Stx2e和EAST1,STb基因仅在一株菌中检测到。多重PCR鉴定结果显示,屠猪肉样品中E.coli主要分布为共生型的A组和B1组。本研究为大肠杆菌病的控制和合理使用抗生素提供实验依据。     

Differentiation of twelve Actinobacillus pleuropneumoniae serotypes by outer membrane lipoprotein gene-based restriction fragment length polymorphism

Twelve Actinobacillus pleuropneumoniae serotypes were differentiated by restriction fragment length polymorphism (RFLP) of polymerase chain reaction (PCR)-amplified fragments from the outer membrane lipoprotein (omlA) gene. All 12 reference serotypes and 80 field isolates produced the expected 950-base pair (bp) fragment of the omlA gene by PCR. Combining the RFLP patterns obtained with SfaNI, Bst71I, AluI, NciI, nine distinct patterns were observed in the 12 serotype reference strains. The PCR-based RFLP analysis of omlA genes allows differentiation among the 12 serotypes, with the exception of group 1 (serotypes 1, 9 and 11), and group 2 (serotypes 2 and 8). When the PCR products from the 70 field isolates were subjected to RFLP analysis, 68 showed the same RFLP patterns as their respective serotype reference strain. Two isolates that could not be typed had the same RFLP patterns as those of serotype 5. These results suggest that PCR-based RFLP analysis of the omlA genes may be of value in differentiating among 12 A. pleuropneumoniae serotypes.     

Sequence and phylogenetic analysis of P10- and P17-encoding genes of avian reovirus

Avian reovirus (ARV) causes viral arthritis, chronic respiratory diseases, and malabsorption syndrome. The P10 protein is a viroporin and induces cell fusion, whereas the biological function of P17 protein is completely unknown. In this study, the nucleotide sequences of the P10- and P17-encoding genes from 17 field isolates and vaccine strains of ARV isolated over a 23-year period from distinct geographic locations were analyzed to define phylogenetic profiles and to study sequence variability and genetic evolution. These genes displayed the signs of a high level of sequence divergence and have evolved into five distinct lineages, respectively. The P17-encoding gene showed higher sequence divergence than that of P10-encoding gene. Our results indicated that synonymous substitutions predominate over nonsynonymous substitutions in both genes. Comparison of P10 and P17 gene phylograms with those of S-class genes revealed distinct evolutionary patterns, indicating that P10 and P17 evolve in an independent manner. Comparative sequence analysis also showed extensive sequence divergence between ARV and other orthoreoviruses. The phylogenetic analysis of P10- and P17-encoding genes revealed that diversity within both genes is neither dependent of viral serotypes nor correlated with the disease states caused by avian reovirus.     

A restriction fragment length polymorphism-based polymerase chain reaction as an alternative to serotyping for identifying Salmonella serotypes

The phase 1 (fliC) and phase 2 (fljB) Salmonella flagella genes were analyzed by restriction fragment length polymorphism (RFLP)-polymerase chain reaction (PCR) to aid in the identification of different Salmonella serotypes. Twenty-four phase 1 flagellin and eight phase 2 flagellin genes could be differentiated among each other with restriction endonucleases Sau3A and HhaI in RFLP-PCR analysis. These flagellin genes comprise the major antigenic formulas for 52 serotypes of Salmonella sp., which include the common serotypes found in poultry and other important food animal species. With the knowledge of the O antigen composition determined from conventional O serotyping, 90% of the Salmonella serotypes could be identified by this double restriction enzyme RFLP analysis of fliC and fljB genes. This RFLP-PCR flagellar typing scheme was successfully applied to the identification of serotype for 112 Salmonella isolates obtained from poultry environment. There was a significant correlation between RFLP-PCR and conventional serotyping (chi-square, P < 0.001). Overall, PCR-RFLP proved to be a fast, accurate, and economical alternative approach to serotyping Salmonella sp.     

鸡传染性支气管炎病毒分子变异机理和免疫机理的研究进展

为阐释鸡传染性支气管炎病毒（avian infectious bronchitis virus，IBV）的高变异特性及其原因，从IBV的不同病变型、分子变异及免疫机理几方面概述了IBV的研究进展，提出了IBV基因组突变、免疫压力和不同毒株基因组间的同源重组所导致的病毒血清型、基因型和组织嗜性的改变是造成免疫失败的主要原因。     

Shiga toxin-producing Escherichia coli in the feces of Alberta feedlot cattle

Shiga toxin-producing Escherichia coli (STEC) are a public health concern. Bacterial culture techniques commonly used to detect E. coli O157:H7 will not detect other STEC serotypes. Feces from cattle and other animals are a source of O157:H7 and other pathogenic serotypes of STEC. The objective of this study was to estimate the pen-level prevalence of Shiga toxins and selected STEC serotypes in pre-slaughter feedlot cattle. Composite fecal samples were cultured and a polymerase chain reaction (PCR) was used to detect genes for Shiga toxins (stx1 and stx2) and genes for O157:H7, O111:H8, and O26:H11 serotypes. Evidence of Shiga toxins was found in 23 pens (92%), O157:H7 in 2 (8%), O111:H8 in 5 (20%), and O26:H11 in 20 (80%) of the 25 pens investigated. Although pen-level prevalence estimates for Shiga toxins and non-O157 serotypes seem high relative to O157:H7, further effort is required to determine the human health significance of non-O157 serotypes of STEC in feedlot cattle.     

Biochemical analysis, cpn60 and 16S rDNA sequence data indicate that Streptococcus suis serotypes 32 and 34, isolated from pigs, are Streptococcus orisratti

Streptococcus suis serotypes have traditionally been identified by morphology, biochemical profiling and serotyping. Analysis of the sequences of 16S rRNA and cpn60 genes of the 35 characterized serotypes of S. suis led to the observation that two serotypes 32 and 34, are significantly distinct from other S. suis serotypes and may represent a distinct species. Here we present DNA sequence data and biochemical profiles which indicate that S. suis serotypes 32 and 34, isolated from pigs, are clustered with Streptococcus orisratti, a Voges-Proskauer negative, alpha-haemolytic, aesculin-hydrolytic, Lancefield group A streptococcus isolated from the teeth of rats.