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.     

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。     

Pathogenesis of infectious bronchitis virus in vaccinated chickens of two different major histocompatibility B complex genotypes

Infectious bronchitis (IB) disease progression in vaccinated chickens after challenge was evaluated in a single commercial line of layer chickens presenting two different major histocompatibility complex (MHC) B complex genotypes. MHC B genotypes were determined by DNA sequence-based typing of BF2 alleles. In total, 33 B2/B15 and 47 B2/B21 chickens were vaccinated with an Ark-type IB virus (IBV) attenuated vaccine and challenged with Ark-type IBV field isolate AL/4614/98 14 days later. Additional chickens of both genotypes served as unvaccinated/challenged and unvaccinated/nonchallenged controls. Clinical signs, histopathologic analysis, detection of IBV genomes in tears, and IBV-specific immunoglobulin A (IgA) in tears were used to evaluate disease progression and immune response. The incidence of IBV respiratory signs was significantly higher in B2/21 than in B2/B15 MHC genotype birds. However, neither the severity and duration of respiratory signs nor the severity and incidence of histologic lesions differed significantly with MHC genotype. The levels of IBV-specific IgA in tears of vaccinated and challenged chickens did not differ significantly between MHC genotypes. IBV genomes were present in the tears of vaccinated and challenged birds, and the incidence of detectable IBV genomes did not vary significantly with MHC B genotype. From an applied perspective, these results indicate that vaccinated commercial outbred chickens with these MHC genotypes are equally resistant to IBV.     

First evidence of the emergence of novel putative infectious bronchitis virus genotypes in Cuba

The emergence of new infectious bronchitis virus (IBV) genotypes or serotypes along with the poor cross-protection observed among IBV serotypes have complicated the avian infectious bronchitis (IB) control programs in different geographic regions. In Cuba, the lack of genetic information regarding IBV and the increasing epidemiological importance of this virus in Cuban chicken flocks demand further characterization of IBV isolates. In the present work, studies of genetic diversity and phylogenetic relationships among recent IBV isolates from Cuban chicken flocks showing respiratory disorders were performed. Two putative genotypes genetically different to the Massachusetts genotype H120 strain used in the Cuban vaccination program were found in the flocks assessed. In addition, a potential nephropathogenic IBV isolate was found by first time in Cuba.     

Serologic and cross-protection studies with several infectious bronchitis virus isolates from Delmarva-reared broiler chickens

Five isolates, from broiler-type chickens, capable of causing acute respiratory disease were identified as infectious bronchitis virus (IBV). The agar-gel precipitin (AGP) test was effective in identifying the isolates as IBV. Virus-neutralization (VN) and cross-challenge tests indicated two of the isolates to be Massachusetts types and one to be a JMK type. The remaining isolates were different from strains normally encountered in chickens reared on the Delmarva Peninsula. One isolate, although serologically similar to the Connecticut strain, was able to infect Connecticut-virus-immune chickens. Another isolate was similar to Arkansas 99, a strain not previously reported in Delmarva.     

鸡传染性支气管炎病毒CQ/01/2004株的分离与鉴定

2004年从重庆某肉用鸡场疑似鸡传染性支气管炎的病鸡中采集病料，按常规处理后接种9～10日龄鸡胚，通过鸡胚连续传代培养3代，并对该分离毒株的鸡胚致病性、血凝性和NDV的干扰特性进行检测．同时进行了动物回归试验。结果表明，该分离株具有IBV感染特征，可使鸡胚胚体出血、蜷缩、矮化；该分离毒株无直接血凝性，对NDV有明显的干扰作用；动物回归试验中有75％的感染鸡在10d内发病或死亡。剖检病死鸡可见肾苍白、肿胀，肾小管内充塞大量尿酸盐，支气管有出血点、有大量粘液。采用反转录．聚合酶链式反应（RT-PCR）技术对CQ／01／2004的纤突蛋白S1基因进行扩增、克隆和序列测定，结果表明该基因具有IBVSl基因的共有分子特征，将测序结果提交GenBank进行同源性检索，发现分离株CQ／01／2004和J株S1的同源性最高，核苷酸同源性为94％，氨基酸同源性为89．4％，与M41的核苷酸同源性为80．6％，氨基酸同源性为78．0％。试验结果表明，分离的病毒株CQ／01／2004为鸡传染性支气管炎病毒。     

鸡传染性支气管炎病毒CK/CH/LHLJ/04V的分离鉴定及致弱的初步研究

从黑龙江省某鸡场发病鸡群的肾脏中分离到一株病毒,通过病毒致SPF鸡胚病变特征、对鸡外周血红细胞凝集特性、病毒粒子形态学特征以及RT-PCR鉴定等方面的研究,表明该病毒为鸡传染性支气管炎病毒,并命名为CK/CH/LHLJ/04V。通过对该病毒基因型分析以及对SPF鸡致病性试验发现该病毒为我国近年来流行的一类重要IBV的代表。将该毒株在SPF鸡胚连续传代110代(P110),取不同代次毒进行动物实验。结果显示,该毒株对SPF雏鸡的致病力随鸡胚传代次数的增加而逐渐降低。P110代毒以105.0 EID50/0.1 mL的剂量通过点眼滴鼻接种15日龄SPF雏鸡,鸡群发病率和死亡率均为0。不同代次毒接种SPF鸡对同源毒株P3代强毒的攻击均具有100%保护性。实验表明,IBV毒株CK/CH/LHLJ/04V P110对SPF雏鸡已无致病性,但仍具有良好的免疫原性,可作为研制IB弱毒疫苗的候选毒株。     

Identification of field isolates of infectious bronchitis virus by interference with the La Sota of strain of Newcastle disease virus

The interference phenomenon of infectious bronchitis virus (IBV) with growth of Newcastle disease virus (NDV) in embryonating chicken eggs (ECE) was used as a diagnostic method. Fifteen field isolates obtained from presumptively infectious-bronchitis-affected chickens were analyzed by the IBV-NDV interference test. Eight isolates were capable of interfering with the growth of the La Sota strain of NDV, as measured by hemagglutination (HA) activity when IBV was inoculated 10 hr before NDV into ECE. The interference was considered specific for IBV, because it could be eliminated by adding homologous anti-IBV serum. The sensibility of this method could be demonstrated, because in some cases low-passage levels of IBV isolates showing HA interference ability were not capable of producing lesions in ECE. Furthermore, serologically negative IBV samples did not interfere with NDV growth. From these results, the IBV-NDV interference test appears to be a potential diagnostic alternative for identifying IBV field isolates.     

Evaluation of the antigen relatedness and efficacy of a single vaccination with different infectious bronchitis virus strains against a challenge with Malaysian variant and QX-like IBV strains

BackgroundThe predominant infectious bronchitis virus (IBV) strains detected in chickens in Malaysia are the Malaysian variant (MV) and QX-like, which are associated with respiratory distress, nephropathy, and high mortality. On the other hand, the antigenic relatedness and efficacy of IBV vaccines against these 2 field IBV strains are not well characterized.ObjectivesThis study aimed to determine the antigen relatedness and efficacy of different IB vaccine strains against a challenge with MV and QX-like strains.MethodsThe antigen relatedness and the ability of different IB vaccine strains in conferring protection against MV and QX-like were assessed based on the clinical signs, macroscopic lesions, and ciliary activity.ResultsThe MV strain IBS037A/2014 showed minor antigenic subtype differences with the vaccine virus Mass H120 and 4/91 strains but showed major antigenic subtype differences with the K2 strain. The Malaysian QX-like strain IBS130/2015 showed major antigenic subtype differences with the MV strain IBS037A/2014 and the vaccine strains except for K2. Chickens vaccinated once with Mass (H120) or with non-Mass (4/91 and K2) developed antibody responses with the highest antibody titer detected in the groups vaccinated with H120 and 4/91. The mean ciliary activities of the vaccinated chickens were between 56 to 59% and 48 to 52% in chickens challenged with IBS037A/2014 and IBS130/2015, respectively. The vaccinated and challenged birds showed mild to severe lesions in the lungs and kidneys.ConclusionsDespite the minor antigenic subtype differences, a single inoculation with Mass or non-Mass vaccines could not protect against the MV IBS037A/2014 and QX-like IBS130/2015.     

鸡传染性支气管炎病毒致病机理的研究进展

鸡传染性支气管是由鸡传染性支气管炎病毒引起鸡的一种急性高度接触性呼吸道传染病,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。文章就该病毒的致病机理方面的研究情况做一综述,为防制鸡传染性支气管炎提供科学依据。     

Protection afforded infectious bronchitis virus-vaccinated sentinel chickens raised in a commercial environment

The protective efficacy of three infectious bronchitis virus (IBV) vaccines for sentinel chickens raised with commercial Delmarva broiler chickens was evaluated during winter 1987. Specific-pathogen-free leghorn sentinel chickens were vaccinated with Massachusetts (Mass) alone, Mass and JMK, or Mass and Arkansas (Ark) combination live vaccines, or they remained unvaccinated. Four weeks post-vaccination, sentinels were placed on broiler farms at weekly intervals for 3 weeks corresponding to weeks 4, 5, and 6 of the broiler growing cycle. Vaccine efficacy was evaluated based on IBV reisolation attempts from tracheal swabbings following a 1-week field exposure period. Sentinel chickens vaccinated with Mass and Ark combination vaccine were best protected against IBV field challenge. Only four IBV isolations were made out of a 3-week total of 36 attempts, for an 11% isolation rate. IBV vaccines containing either Mass alone or Mass and JMK offered much lower levels of protection.     

Protective immunity to infectious bronchitis in broilers vaccinated against Marek's disease either in ovo or at hatch and against infectious bronchitis at hatch

Two experiments were conducted using commercial broiler chickens to determine if Marek's disease (MD) vaccines HVT/SB-1 and HVT plus CVI-988 given either in ovo or at hatch adversely affected the efficacy of infectious bronchitis (IB) vaccines (Ark and Mass serotypes) given by eyedrop on the day of hatch. Nonvaccinated negative controls and controls that received only IB vaccines were included in each study. Birds were challenged with either infectious bronchitis virus (IBV) Mass-41 or IBV Ark-99 on either day 26 or 27 of age. Protection was assessed 5 days post-IBV challenged by virus isolation from the trachea. The day of hatch mean antibody titer to IBV was 12,668 +/- 4704 and 2503 +/- 3243 by enzyme-linked immunosorbent assay in experiments 1 and 2, respectively. In each study, nonvaccinated controls had a significantly higher (P < or = 0.05) incidence (88%-100%) of IBV challenge virus isolation than did controls vaccinated for IB but not for MD. Analysis of data from both studies showed that protection to IB in groups that received only IB vaccines at hatch ranged from 55.0% to 77.3%, whereas protection to IB in groups receiving both MD and IB vaccines ranged from 50.0% to 95.5%. In both experiments and within IBV challenge serotype, broilers given MD vaccines (in ovo or at hatch) and IB vaccines at hatch had protection rates to IBV challenges that were not significantly less (P < or = 0.05) than IB protection rates of groups that received only IB vaccines at hatch. Analysis of these data shows that administration of high-titered MD vaccines either in ovo or at hatch did not affect the efficacy of an IB vaccination (serotypes Ark and Mass) given by eyedrop at hatch.     

Infectious bronchitis virus nucleoprotein specific CTL response is generated prior to serum IgG

Infectious bronchitis (IB) is an acute and highly contagious viral respiratory disease of chickens. To understand the kinetics and relationships between the humoral (Ab) and antigen specific T cell immunity as well as pathological changes during infectious bronchitis virus (IBV) infection and immunization, one-week-old SPF chickens were vaccinated with live IBV H52 strain and challenged with IBV M41 15 days post primary infection. Chickens were sacrificed every 3 days to monitor antigen specific serum IgG and IBV nucleoprotein-specific immune responses using a chicken MHC I tetramer developed in our laboratory. The results demonstrated that T cell responses developed more rapidly than the humoral (Ab) immune response after vaccination with H52. However, serum IgG dramatically increased after M41 challenge. Chickens from the control, non-vaccinated group developed severe respiratory symptoms and demonstrated significant pathological changes in lung, kidney and bursa of Fabricius post challenge with M41. However, chickens vaccinated with H52 did not demonstrate clinical signs or histological changes post challenge with M41. These results indicated that the live IBV H52 inoculation effectively protected chickens from morbidity and pathological changes associated with IBV infection. These data facilitates the design of a new generation of IBV vaccine.     

不同来源传染性支气管炎病毒诱导SPF鸡发病的免疫机制研究

试验旨在探讨不同来源的传染性支气管炎病毒(Infectious bronchitis virus,IBV)诱导SPF鸡发病的免疫机制。选用140只1日龄SPF白来航鸡,随机分为4组,3组攻毒组通过滴鼻点眼途径分别接种鸡源IBV强毒株、鸡源IBV弱毒株和野鸡源IBV毒株3个毒株,对照组以同种方式接种等量灭菌的磷酸盐缓冲液。在感染后12 h、36 h、72 h、7 d和14 d,每组随机选取5只进行剖检,并分别采集法氏囊、肾脏和气管组织,剩余鸡用于观察临床症状、发病及死亡情况。应用实时荧光定量PCR检测攻毒后不同时间点采集的各组织中IBV的病毒载量、Toll样受体(Toll-like receptors,TLRs)及部分细胞因子(白细胞介素(interleukin,IL)和干扰素(interferon,IFN))表达量的变化。结果显示,感染不同来源IBV毒株之后仅鸡源IBV强毒株感染组SPF鸡出现抑郁、翅膀下垂、甩头等典型的临床症状,且在感染后5~10 d共有7只死亡,死亡率为20%。病理剖检发现,感染鸡源IBV强毒株的鸡肾脏肿大、尿酸盐沉积和有花斑样病变,而感染野鸡源IBV毒株、鸡源IBV弱毒株和对照组的鸡无明显的眼观病变。实时荧光定量PCR结果显示,在鸡源IBV强毒株组的法氏囊、肾脏和气管3个组织中均检测到病毒。对照组和野鸡源IBV毒株组中均未检测到病毒,鸡源IBV弱毒株组只在部分组织中检测到病毒。在感染后72 h,鸡源IBV强毒株组与其他各组相比,TLR1、TLR2、TLR3、TLR5、TLR7和TLR15基因在法氏囊中的表达量均显著升高(P<0.05),IL-6和IFN-β参与更强烈的抗病毒免疫反应;在感染后7 d,鸡源IBV弱毒株组与其他各组相比,肾脏中TLR2、TLR3、TLR15、TLR21、IL-6和IL-18基因表达量均显著升高(P<0.05)。野鸡源IBV感染后36 h法氏囊组织中IFN-γ基因表达量显著上调(P<0.05)。综上所述,3个IBV毒株中仅鸡源IBV强毒感染引起SPF鸡典型临床发病症状与可视组织病变,且可提高SPF鸡组织中免疫相关因子的基因表达量。本研究结果揭示,不同来源的IBV对SPF鸡的不同致病性与其感染诱导的免疫反应不同有关。     

鸡传染性支气管炎强毒分离株遗传进化分析和免疫保护试验

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。     

Phylogenetic analysis of S1 gene of infectious bronchitis virus isolates from China

Between 2006 and 2009, seven strains of infectious bronchitis (IB) virus (IBV) were isolated from vaccinated chicken flocks on different chicken farms in China. The pathogenic characters of seven IBV strains were assessed. Each of the seven strains was infective to the test chickens and could induce an immune response. The results from chicken embryo cross-neutralization assays showed that these strains were antigenically distinct from classic IBV strains of H120, M41, Conn, and Gray. Compared to H120 vaccine strain, point mutation, short insertion, and deletion occurred at many positions in the S1 protein of the seven strains. Five of the seven strains had the motif (HRRRR), which was identical to that of the epidemic IBV strains in China. Two new motifs (HRLRR and RRIRR) emerged in the isolated strains. The homology of the nucleotide and amino acid sequences of the S1 gene among the seven isolates was 81.7%-99.7% and 79.0%-99.4%, respectively. These seven strains were also genetically different from the vaccine strains and non-China IBV strains but closely related to large numbers of Chinese strains. The seven isolates and 36 reference IBV strains were clustered into six distinct groups (I-VI). The seven strains were categorized into groups I, II, and III, forming a big phylogenetic branch, which is closely related to Chinese IBVs, whereas the vaccine strains belonging to group VI are genetically distant from groups I, II, and III. The results from this study indicate that different IBV strains cocirculate in the chicken population in China.     

Pathogenicity and antigenicity of a new variant of Korean nephropathogenic infectious bronchitis virus

Despite the existence of an active vaccination program, recently emerged strains of nephropathogenic infectious bronchitis virus (IBV) in Korea have caused significant economic losses in the poultry industry. In this study, we assessed the pathogenic and antigenic characteristics of a K-IIb type field strain of IBV that emerged in Korea since 2003, such as Kr/Q43/06. Specific pathogen free 1-week-old chickens exhibited severe respiratory symptoms (dyspnea) and nephropathogenic lesions (swollen kidneys with nephritis and urate deposits) following challenge with the recent IBV field strain. The antigenic relatedness (R value), based on a calculated virus neutralization index, of the K-IIb type field strain and K-IIa type strain KM91 (isolated in 1991) was 30%, which indicated that the recent strain, Kr/Q43/06, is a new variant that is antigenically distinct from strain KM91. This report is the first to document the emergence of a new antigenic variant of nephropathogenic IBV in chicken from Korea.     

Determination of the antigenic relationships within the Massachusetts (M41) type of infectious bronchitis virus using the hemagglutination-inhibition test

The antigenic relationships, antigenic spectrum, and immunogenicity of seven IBV-Massachusetts-41 isolates were investigated using the hemagglutination-inhibition (HI) test. HI titers equal to 32 are considered suspicious, titers lower than 32 are considered negative, and titers higher than 32 are considered positive immune responses to infectious bronchitis virus (IBV). Some isolates of Massachusetts-41 ( M41 ) were capable of inducing large quantities of antibodies in chickens following inoculation and demonstrated a wider antigenic spectrum than others. Variations in antigenic spectrum observed within M41 isolates in this study are in agreement with previous reports. This variation is of importance in selecting a proper vaccine strain for a successful immunization program for IBV.     

鸡传染性支气管炎病毒地方流行株的分离与鉴定

从山西各地区疑似鸡传染性支气管炎(IB)的病料中,分离到5株鸡传染性支气管炎病毒(IBV)分离株,并对分离病毒进行了病毒形态观察、对鸡新城疫病毒(NDV)的干扰、鸡胚致病性试验、动物回归试验、血凝特性试验、病毒理化特性测定等生物特性鉴定及IBV N基因特异性片段的检测.电镜观察,可见直径为60～120 am,有囊膜及纤突呈冠状排列的病毒粒子;对NDV有明显的干扰作用;分离株的传代物均有明显的致鸡胚矮小化作用;动物回归感染死亡鸡肾脏病变明显,表现肾脏肿大、花斑肾现象,输尿管内充塞大量尿酸盐;无直接血凝性,经1%胰酶处理后可凝集鸡红细胞;分离株对乙醚和氯仿敏感;采用反转录-聚合酶链式反应(RT-PCR)对分离毒株进行扩增,结果均扩增出特异N基因核酸片段.     

IgM responses in chicken serum to live and inactivated infectious bronchitis virus vaccines.

Intramuscular (i.m.) administration of infectious bronchitis virus (IBV) oil-emulsion vaccine (OEV) to IBV-primed or unprimed chickens resulted in the production of zero or minimal concentrations of IBV-specific IgM in the serum, as measured by enzyme-linked immunosorbent assay of gel chromatography fractions. Live-attenuated infectious bronchitis (IB) vaccine given i.m. or by eyedrop stimulated the production of IBV-specific IgM in similar amounts following inoculation by both routes. These levels were comparable to those found in earlier studies following intranasal inoculation with a virulent strain of IBV and confirm that the detection of IBV-specific IgM is a valuable aid to the diagnosis of recent infection. As expected, administration of live-attenuated IB vaccines i.m. or by eyedrop protected the respiratory tract against challenge with virulent virus 24 days later; however, OEV given i.m. did not.