山东地区鸡传染性支气管炎病毒抗原相关性和血清分型

为进一步明确山东地区鸡传染性支气管炎病毒(IBV)的流行病学,对IBV分离株之间以及与疫苗株之间的抗原相关性进行了分析。分别制备了3个疫苗株(4/91、H120和Ma5)和18个分离株的单因子阳性血清,通过鸡胚交叉中和试验测定了阳性血清对同源病毒和异源病毒的中和效价,计算了不同毒株之间的抗原相关系数(R值),并根据R值进行血清分型。结果显示,3个疫苗株和18个分离株可分为5个血清型。疫苗株4/91属于血清Ⅰ型,H120、Ma5与2个分离株(SDWF0608和SDLY0701)属于同一血清型,分离株SDZB0808与SDLY0702、CK/CH/SD08/007和CK/CH/SD09/001等15个毒株为同一血清型,CK/CH/SD09/006和CK/CH/SD10/001分别与其他3和6个分离株组成两个血清型。进一步分析发现,部分IBV毒株之间表现单向中和反应性,属于同一血清型的IBV毒株之间抗原相关性可能存在明显差异。本研究结果一方面表明IBV毒株之间复杂的抗原相关性,另一方面显示IBV流行株与3个疫苗株之间抗原性存在明显差异。     

鸡传染性支气管炎病毒山西地方分离株的血清学分析

应用病毒感染的鸡胚材料免疫兔的方法制备抗鸡传染性支气管炎病毒(IBV)单因子血清,然后在鸡胚上对山西分离的6个毒株和6个参考株进行交叉病毒中和试验。结果显示,这6株病毒与参考毒株不属于同种血清型,但分离株之间存在部分交叉免疫保护,证实了鸡传染性支气管炎病毒毒株在山西地区存在变异。     

不同免疫血清对鸡传染性支气管炎病毒血清型鉴定的影响

鸡传染性支气管炎病毒 ( avian infectious bron-chitis virus,IBV)由于其血清型众多 ,在预防该病时 ,常因所用疫苗株与流行株血清型不同而导致免疫失败[1,2 ] 。因而国内外学者普遍认为 ,IB研究的重点应放在 IBV血清型的鉴定和研制相应的弱毒疫苗和灭活疫苗上 [3 ]。国外已成功地将血凝抑制试验 ( HI)应用到不同 IBV毒株的血清分型上 ,King和 Hopkins[4 ] 证明HI试验是一种快速、简便的 IBV分型方法。但在应用该法进行 IBV分型时 ,常会遇到选择免疫血清的问题。本文比较了 3种免疫血清在 HI法中对 IBV血清分型的影响 ,得到了可…     

传染性支气管炎病毒分离株的生物学特性鉴定及其遗传变异分析

通过鸡胚矮小试验、鸡胚气管环组织培养试验、干扰新城疫病毒复制试验和动物回归试验,将2006-2007年在江苏省分离的7株鸡传染性支气管炎病毒（IBV）鉴定为嗜肾型毒株。采用RT-PCR扩增IBV分离株的S1基因,并进行克隆和序列分析。结果显示7个IBV分离株S1基因的核苷酸同源性为94．6％-99．4％,处于同一个群,分别属于3个亚群。这些毒株与大多数国内近年分离株的同源性较高,而与Massachusetts、T、4／91和793B血清型毒株（包括H120和H52疫苗毒株）的同源性较低。IBV流行毒株和疫苗毒株的差异是造成免疫鸡群发生传染性支气管炎的重要原因。     

传染性法氏囊病病毒广西分离株血清亚型的确定

应用兔制备的抗传染性法氏囊病病毒(IBDV)高免血清,在鸡胚成纤维细胞(CEF)上对从广西发病鸡群分离的4个IBDV代表性流行毒株和2个常用疫苗株进行交叉中和试验。结果表明6个毒株被分为2个血清亚型;根据试验所得的R值,应用聚类分析法分析了各亚型毒株之间的亲缘关系,结果显示目前在广西流行的IBDV野毒株之间以及其与疫苗株间的抗原性存在一定的差异。研究结果对及时掌握广西IBDV流行毒株的抗原变异并为研制更有效的适合本地使用的IBD疫苗提供了科学依据。     

一株鸡传染性支气管炎病毒的鉴定及S1基因序列分析

将分离到的一株疑似鸡传染性支气管炎病毒接种SPF鸡胚增殖,通过致鸡胚矮小化试验、红细胞凝集试验、对新城疫病毒增殖干扰试验、动物回归试验及RT-PCR分子鉴定,结果证实该病毒为鸡传染性支气管炎病毒(IBV)。应用MEGA5分析软件,与Gen Bank上IBV常见疫苗株、流行毒株和部分参考株进行序列比对,其S1基因序列与近年来我国流行毒株同源性较高,为95%~99%,与传统疫苗株H120、H52、M41和W93同源性较低,仅为77%~79%。     

鸡传染性支气管炎病毒M41株鸡胚增殖工艺研究

为研究鸡传染性支气管炎病毒(IBV)M41标准毒株在鸡胚上的最佳生产工艺,试验用IBV M41株分别以不同剂量接种同一胚龄不同鸡胚、不同胚龄普通鸡胚,以及IBV M41株接种普通鸡胚后不同培养时间收获鸡胚尿囊液,比较不同培养条件下制备病毒液的产量及病毒效价。结果显示:IBV M41株接种无传染性支气管炎病毒母源抗体的SPF鸡胚最佳病毒接种剂量为104.5EID50,接种含有IBV母源抗体的普通鸡胚最佳病毒接种剂量为105.1EID50,最佳接种胚龄为11日胚龄,最佳收毒时间为48 h。按照此工艺制备疫苗,免疫SPF鸡,IBV抗体效价均符合规程标准。研究结果为用鸡胚高效、大量生产IBV M41株病毒抗原进而生产合格的IB疫苗提供了数据支持。     

传染性支气管炎CK/CH/HD/190716株的分离鉴定与全基因组分析

对河北某免疫鸡场采集疑似感染传染性支气管炎病毒(IBV)鸡的肺脏进行病毒分离,并通过鸡胚接种和全基因序列测定分析,对分离病毒进行鉴定和遗传变异分析。分离到1株IBV,命名为CK/CH/HD/190716,该病毒接种鸡胚后可产生IBV特征性的侏儒胚。该病毒基因组总长为27 680 bp,其中Ploy A尾含有16个A。将分离株基因序列与不同基因型的IBV毒株进行同源比对,构建遗传进化树进行基因分型,证实该毒株属于QX型。选取我国分离的14株QX型IBV与之比较同源性,发现该型病毒全基因组的同源性在93%～97%,但是5a基因的同源性最低,只有80%,表明IBV各基因之间的进化具有显著差异。随后通过多个重组软件分析证实,该毒株的1a基因部分区域由QX型野毒KX425847和KU317090重组产生。本试验揭示了我国流行的QX型IBV存在基因多样性,需要对该型病毒的遗传演化进行密切监测。     

鸡传染性支气管炎病毒基因型与血清型相关性初步研究

为研究鸡传染性支气管炎病毒(IBV)基因型与血清型之间的相关性,本研究以国内不同地区的17株IBV分离株、2株疫苗株(M41、W93)和1株强毒株(X株)为研究对象,经RT-PCR扩增获得20株IBV的S1基因并进行测序.将其分别与GenBank中的20株国内外参考IBV株的S1基因进行序列比较,绘制S1基因系统进化树...     

鸡传染性支气管炎病毒野毒株的鉴定

鸡传染性支气管炎(Infectious bronchitis,IB)病毒血清型众多,且不断出现新的变异株,疫苗免疫后鸡群发病现象仍时有发生,给养禽业造成巨大的经济损失。本文对免疫失败发病的疑似病料进行了鸡传染性支气管炎病毒(Infectious bronchitis virus,IBV)RT-PCR,并与市售的IB疫苗毒株进行了序列比对分析,确定了该疑似病料为IBV 793/B型野毒感染,而非疫苗株。     

Differentiation of vaccine strains and Georgia field isolates of infectious laryngotracheitis virus by their restriction endonuclease fragment patterns

Seven restriction endonucleases (REs) were used to cleave the DNA from seven vaccine strains of infectious laryngotracheitis (ILT) virus and from six Georgia field isolates of ILT virus. After electrophoresis of the resulting RE fragments, the patterns were compared in order to differentiate strains of ILT virus. The six chicken-embryo-origin (CEO) vaccines were identical with each RE, but the tissue-culture-origin (TCO) vaccine strain differed from the CEO vaccines using five of the REs. Four of the six field isolates were identical by each RE, but two field isolates differed from each other and from the four identical field isolates on the basis of patterns produced by some but not all of the REs. The four identical field isolates could not be differentiated from the CEO vaccine strains by any RE, but the other two field isolates were not identical to either strain of vaccine virus. This work demonstrates that differentiable strains of ILT virus exist in the United States and that viruses other than vaccine viruses are involved in field outbreaks of ILT.     

Molecular epidemiology of classical swine fever in the Russian Federation

The ability to discriminate between various classical swine fever virus (CSFV) strains and isolates is a prerequisite for following the spread of the virus after an outbreak. To determine the relatedness between Russian CSFV isolates from different geographical regions, three fragments of the viral genome (5' NTR, the variable region of the E2 gene and a fragment of the NS5B gene) were sequenced and used for genetic typing. Thirty-one field isolates were obtained from CSF outbreaks which occurred between 1994 and 1999. In addition, three attenuated strains were included in the study, namely the LK and CS vaccine strains, and the moderately virulent 238H isolate. The vaccine strains have been used in Russia for more than 30 years. Our results showed that all field isolates are in subgroup 1.1 together with Alfort 187 and with the highly virulent strain Shimen. In contrast, the CS and LK vaccine strains belong to subgroup 1.2. While there is no evidence for the reversion of the two vaccine strains to wild type, it is feasible that the highly virulent Shimen strain, which has been used as a challenge strain for many years, contributed to field strain generation. The Russian field isolates from the 1990s can be distinguished from the CSF virus isolates which occurred in the EU Member States in the same decade, as here all outbreaks were caused by CSF viruses belonging to subgroup 2.     

Vaccine efficacy against Ontario isolates of infectious bronchitis virus

Infectious bronchitis (IB) is an economically important viral disease with worldwide distribution. Every country with an intensive poultry industry has infectious bronchitis virus (IBV). The virus rapidly spreads from bird to bird through horizontal transmission by aerosol or ingestion. Sentinel bird studies were carried out in southern Ontario and IBV has been isolated from layer flocks. Genetic analysis of the S1 region of the strains showed that they were not vaccine related. The pathogenicity of selected Ontario variants of IBV isolates was studied and the subsequent work was to determine the degree of protection against field isolates provided by a commonly used vaccine MILDVAC-Ma5 in Ontario. The protection was evaluated by challenging immunized chickens with the respiratory (IBV-ON1) and nephropathogenic (IBV-ON4) viruses. The mean vaccine efficacy for IBV-ON1 was 66.7% indicating that a Massachusetts serotype vaccine would provide some protection against IBV field isolates.     

New serotype 2 and attenuated serotype 1 Marek's disease vaccine viruses: comparative efficacy

Attempts were made, through selection of optimum viral strains, to develop improved vaccines against Marek's disease (MD). Seven attenuated serotype 1 strains and 22 avirulent serotype 2 strains, both alone and in combination with the FC126 strain of serotype 3, were screened for protective efficacy against challenge with virulent and very virulent MD viral strains. The three viruses selected as most promising were evaluated alone and in various combinations and compared with commercially available vaccines, including FC126, bivalent (FC126 + SB-1), and CV1988/C, in 12 separate assays. Two of these new viruses--301B/1 (serotype 2) and Md11/75C/R2 (serotype 1)--were exceptionally protective compared with prototype vaccine strains. Four new monovalent and polyvalent vaccines based on these two isolates protected chickens better than FC126 alone or CV1988/C alone. Three of these new vaccines provided better protection than the bivalent (FC126 + SB-1) vaccine. Protective synergism was noted commonly between viruses of serotypes 2 and 3 but only sporadically between serotypes 1 and 2 or between serotypes 1 and 3. Strain CVI988/C was protective but was no better than FC126 alone, and it was less effective than bivalent (FC126 + SB-1) vaccine, even when used as a bivalent vaccine with FC126 or SB-1.     

VP2-segment sequence analysis of some isolates of bluetongue virus recovered in the Mediterranean basin during the 1998-2003 outbreak

The complete nucleotide sequences of the VP2 segments of bluetongue virus (BTV) isolates recovered from Italy, Greece and Israel, from 1998 to 2003, were determined. Phylogenetic analysis of these sequences, those from related viruses and the South African vaccine strains, were used to determine the probable geographic origin of BTV incursions into Italy. Results indicated that viruses from each of the four serotypes isolated in Italy (2, 4, 9 and 16) possibly had a different origin. Analysis of the bluetongue virus serotype 2 (BTV-2) isolates gave evidence that this serotype probably moved from Tunisia. BTV-4 results showed probable incursion from the southwest and not from Greece or Israel. BTV-9 isolates clearly have an eastern origin (most probably Greece), whereas BTV-16 isolates are indistinguishable from the BTV-16 live attenuated vaccine strain. The phylogenetic findings were supported by polyacrylamide gel electrophoresis (PAGE) analysis of the complete amplified genome of each isolate except for BTV-16 Italian field isolate, which showed a slightly different PAGE profile. A combination of the complete VP2 sequencing and PAGE analysis of complete genomes, allowed not only phylogenetic analysis, but also vaccine detection and assessment of reassortment events.     

VP2‐segment Sequence Analysis of Some Isolates of Bluetongue Virus Recovered in the Mediterranean Basin During the 1998–2003 Outbreak

The complete nucleotide sequences of the VP2 segments of bluetongue virus (BTV) isolates recovered from Italy, Greece and Israel, from 1998 to 2003, were determined. Phylogenetic analysis of these sequences, those from related viruses and the South African vaccine strains, were used to determine the probable geographic origin of BTV incursions into Italy. Results indicated that viruses from each of the four serotypes isolated in Italy (2, 4, 9 and 16) possibly had a different origin. Analysis of the bluetongue virus serotype 2 (BTV‐2) isolates gave evidence that this serotype probably moved from Tunisia. BTV‐4 results showed probable incursion from the southwest and not from Greece or Israel. BTV‐9 isolates clearly have an eastern origin (most probably Greece), whereas BTV‐16 isolates are indistinguishable from the BTV‐16 live attenuated vaccine strain. The phylogenetic findings were supported by polyacrylamide gel electrophoresis (PAGE) analysis of the complete amplified genome of each isolate except for BTV‐16 Italian field isolate, which showed a slightly different PAGE profile. A combination of the complete VP2 sequencing and PAGE analysis of complete genomes, allowed not only phylogenetic analysis, but also vaccine detection and assessment of reassortment events.     

Occurrence and significance of infectious bronchitis virus variant strains in egg and broiler production in the Netherlands

Despite vaccination against Infectious bronchitis virus (IBV) with the Massachusetts type vaccine viruses H120 and H52 in the Netherlands, an increasing number of properly vaccinated flocks have suffered from the disease since 1978. In the years 1978-1982, the virus was isolated from 162 IBV suspected flocks. Cross-virus-neutralization tests showed that the majority (67 per cent) of these isolates belonged to serotypes other than the Massachusetts type, the Connecticut-, Florida-, Iowa 97-, Iowa 609- and JMK serotype. The majority of these Dutch isolates could be divided into 4 serogroups, called D207, D212, D3128 and D3896. Only a few isolates were not related to these serotypes. A survey of 328 flocks for antibody against these serotypes demonstrated that antibody against one or more of these novel serotypes were present in most of the flocks. Experiments demonstrated that vaccination with the H120 vaccine virus was not able to protect chickens against the adverse effects of a challenge with the novel serotypes.     

Molecular and serologic characterization, pathogenicity, and protection studies with infectious bronchitis virus field isolates from California

In this study, we characterized three variant infectious bronchitis virus (IBV) strains isolated in 2003 and 2004 from broiler chickens in California and compared them to previously isolated California variant viruses and to common vaccine serotypes used in the United States. We conducted genetic, serologic, and pathogenicity studies on all three isolates, then tested different vaccines against one of the viruses. Genetically the three variant IBV strains, designated CA557/03, CA706/03, and CA1737/04, were not related to each other. GenBank BLAST database search and phylogenetic analysis of the hypervariable region of the S1 subunit of the spike gene to determine the most closely related viruses to the three variants showed the CA557/03 variant to be 81.8% similar to the CAV/CA56b/91 whereas the CA706/03 and CA1737/04 variant viruses were only distantly related to Dutch/D1466/81 (72.2%), a vaccine strain used in Europe, and Korea/K142/02 (72.7%), a Korean field isolate, respectively. Cross virus-neutralization testing showed that none of the 2003-04 California IBV variant viruses were serologically related to each other or to Ark, Conn, or Mass vaccine strains. In addition the CA1737/04 isolate was also tested against DE072 and found not to be serologically related. All three variant viruses were pathogenic in 1-wk-old broilers and vaccination with Mass/Conn followed by Holland/Conn provided 80% protection against the CA1737/04 virus. The 2003-04 California variant viruses were not compared with variants isolated in California during 1970s and 1980s because, to our knowledge, no genetic information is available and those viruses are no longer obtainable. This study shows that the CA557/03 virus was distantly related to the CAV-type viruses isolated in California in the early 1990s, but that none of the 2003-04 viruses were similar genetically or serologically to the CAL99-type viruses, indicating that new IBV variants continue to emerge and cause disease in commercial chickens in California.     

Variation amongst the neutralizing epitopes of bluetongue viruses isolated in the United States in 1979-1981.

Neutralizing epitopes present on field isolates of bluetongue virus (BTV) serotypes 10, 11, 13 and 17 were evaluated with a panel of polyclonal and neutralizing monoclonal antibodies (MAbs). A total of 91 field isolates were evaluated, including 15 isolates of BTV-10, 29 isolates of BTV-11, 26 isolates of BTV-13, and 21 isolates of BTV-17. The viruses were isolated from cattle, goats, sheep, elk and deer in Idaho, Louisiana, Nebraska and, predominantly, California, in the years 1979, 1980 and 1981. The isolates were analyzed and compared using a panel of neutralizing MAbs which included five MAbs raised against BTV-2, seven against BTV-10, five against BTV-13, and six against BTV-17. Neutralization patterns obtained with the MAb panel and individual field isolates were compared to those obtained with prototype viruses of each serotype. All field isolates were neutralized by at least some of the MAbs raised against the prototype virus of the same serotype. All field isolates of BTV-10 were neutralized by the seven MAbs raised to BTV-10, whereas the field isolates of BTV-11, BTV-13 and BTV-17 were not consistently neutralized by all of the MAbs raised against the prototype virus of the same serotype. Variation in neutralizing epitopes recognized by the MAb panel was most pronounced amongst the field isolates of BTV-17. A one-way cross neutralization was evident between BTV-10 and BTV-17 as all field isolates of BTV-17 were neutralized by four of the MAbs raised against BTV-10. In contrast, no BTV-10 isolates were neutralized by the MAbs raised against BTV-17. Differences in the MAb neutralization patterns of field isolates of BTV-11, BTV-13 and BTV-17 suggest that the immunogenic domain responsible for their neutralization is plastic, such that individual epitopes within the domain may vary in their significance to the neutralization of different viruses, even of the same serotype. The apparent conservation of neutralizing epitopes on field isolates of BTV-10 suggests that the field isolates may be derived from the modified-live vaccine strain of BTV-10.