Comparison of two infectious bursal disease vaccine strains: efficacy and potential hazards in susceptible and maternally immune birds.

Two infectious bursal disease vaccines were administered to separate groups of maternally immune and susceptible chickens at various ages. Vaccine B caused no damage to the bursae of chickens examined histologically at nine and 20 days after vaccination. The bursae of chickens given vaccine A were shown to be severely damaged when similarly examined. Both vaccines protected all the susceptible groups against challenge, but only vaccine A protected the groups of maternally immune chickens. Susceptible chickens vaccinated at one day of age with vaccine A showed a lowered response to Hitchner B1 Newcastle disease vaccine given at 14 days of age, judged by the haemagglutination-inhibition response and Newcastle disease challenge. The performance of the Newcastle disease vaccine was not affected in chickens given vaccine B. Bedding used by birds given vaccine A was shown to be capable of transmitting vaccinal virus to susceptible chickens, causing severe bursal damage.     

法氏囊提取液对新城疫活疫苗免疫效力的影响

本文对鸡法氏囊提取液与ND活疫苗的使用方法进行了分析。通过血凝抑制抗体滴度的测定结果表明,预先接种鸡法氏囊提取液时,经肌肉注射、口服和点眼滴鼻接种方式均能提高ND疫苗免疫鸡的抗体产生能力,且经肌肉注射法最佳。但是,在整个试验期间,法氏囊提取液只能增强鸡群对ND活疫苗的早期免疫应答,而法氏囊提取液与ND活疫苗同时使用时更能刺激免疫鸡群的早期抗体产生水平。     

Vaccination of day-old broiler chicks against Newcastle disease and infectious bursal disease using commercial live and/or inactivated vaccines

Day-old broilers were administered live and/or inactivated vaccines to assess vaccine efficacy against challenge with Newcastle disease (ND) and infectious bursal disease (IBD). Chicks were from commercial breeder pullets vaccinated against ND and IBD using several live vaccine primers followed by an inactivated ND-IBD vaccine at 18 weeks. The most efficacious initial ND-IBD vaccination program was live ND virus by eye drop and live IBD vaccine injected subcutaneously (SQ) followed 2 hours later with inactivated ND-IBD vaccine SQ. The next two most efficacious programs were live vaccine alone and the inactivated vaccine only. Inactivated vaccine given SQ had no adverse effect on live IBD vaccine given 2 hours earlier in a similar site. Administration of inactivated vaccine by vent was not as efficacious as administration SQ. A booster of a second live ND-IBD vaccine drinking water at 18 days significantly increased levels of circulating antibody, regardless of the initial vaccination program.     

鸡新城疫和传染性法氏囊病灭活疫苗抗原量对鸡细胞免疫的影响

将不同抗原含量的鸡新城疫和传染性法氏囊病油乳剂灭活疫苗分别免疫１７日龄雏鸡，测定了疫苗抗原含量与细胞免疫应答之间的关系。经Ｔ淋巴细胞转化试验结果表明，两种疫苗的抗原含量－细胞免疫应答曲线是一致的，随着抗原量的增加，活化的Ｔ淋巴细胞数量也相应增多，但是细胞免疫应答的可测时间是暂时的，于免疫７天达高峰，１７天后下降接近正常水平。     

Immunoreactivity and morphological changes of bursal follicles in chickens infected with vaccine or wild-type strains of the infectious bursal disease virus

Infectious bursal disease (IBD) is characterized by immunosuppression due to the depletion of lymphocytes in the atrophied bursa of Fabricius (BF). We have sometimes encountered contradictory findings: chickens infected with the vaccine IBD virus (IBDV) strain have sometimes exhibited a highly atrophied BF, but not immunosuppression. In this study, chickens administered vaccine or wild-type strains of IBDV were later vaccinated with the B1 strain of the Newcastle disease virus (NDV). Bursal changes were examined histologically with a focus on the bursal follicle. The immunoreactivity to NDV was also evaluated with the hemagglutination inhibition test. In gross examination, we observed a few chickens with a severely atrophied BF in vaccine strain-administered groups (vaccine groups), and the level of severity was the same as that in the wild-type strain-administered group (wild-type group). However, these chickens retained humoral antibody responses to NDV and were revealed to possess a higher number of bursal follicles than those of the wild-type group. These results indicated that macroscopic evaluation dose not accurately reflect the immunoreactivity and degree of bursal damage in IBDV-administered chickens. We also found non-immunosuppressed chickens in the wild-type group. These non-immunosuppressed chickens retained a significantly higher number of normal follicles and total follicles according to our statistical analysis. Furthermore, a high correlation coefficient between the NDV-HI titer and the number of normal follicles was found in the wild-type group. These results implied that the retained number of normal follicles is important for the immunoreactivity of chickens infected with IBDV.     

Pathological and immunological study of an in ovo complex vaccine against infectious bursal disease

The appearance of very virulent strains of infectious bursal disease (IBD) virus at the end of the 1980s made it necessary to develop more effective immunization procedures. To facilitate this, the immunogenicity and the immunosuppressive effect of a mild (G-87), an intermediate (LIBD) and an intermediate-plus (IBDV 2512) IBDV strain were tested after the in ovo inoculation of 18-day-old SPF and broiler chicken embryos. It was established that no noteworthy difference existed between the immunized and the control embryos in hatching rate and hatching weight. The higher the virulence of the vaccine virus strain, the more severe damage it caused to the lymphocytes of the bursa of Fabricius. In SPF chickens, the haemagglutination inhibition (HI) titres induced by a Newcastle disease (ND) vaccine administered at day old decreased in inverse ratio to the virulence of the IBD vaccine strain, while in broiler chickens this was not observed. Despite the decrease of the HI titre, the level of protection did not decline, or did so only after the use of the 'hot' strain. SPF chickens immunized in ovo with a complex vaccine prepared from strain IBDV 2512 and IBD antibody showed the same protection against Newcastle disease as the broilers. In broiler chicken embryos immunized in ovo, only strain IBDV 2512 induced antibody production, and such chickens were protected against IBD at 3 weeks of age. The complex vaccine administered in ovo has been used successfully at farm hatcheries as well.     

Immunosuppressive effect of infectious bursal disease virus strains of variable virulence for chickens.

Infection of chicks with attenuated Lp and Sp clones of the RF-1 strain of infectious bursal disease virus was shown to exert no immunosuppressive effect, whereas the parent strain RF-1tc and the original virulent strain RF-1wt were immunosuppressive. One-day-old chicks infected with Lp and Sp clones showed no suppression of immunological response to live Newcastle disease vaccines B1 and TCND, and to bivalent infectious coryza vaccine. On the other hand, infection with RF-1tc or RF-1wt strains was immunosuppressive for these vaccines. The immunosuppressive effect of RF-1tc and RF-1wt strains was more pronounced for infectious coryza vaccine and B1 vaccine than for TCND vaccine. The immunosuppressive effect of RF-1tc and RF-1wt strains was lower when chicks were infected with these strains at the age of 21 days than when they were infected at one day of age.     

Recovery of antibody-producing ability and lymphocyte repopulation of bursal follicles in chickens exposed to infectious bursal disease virus.

We studied the long-term effect of infectious bursal disease virus (IBDV) in chickens. Specifically, the restoration of virus-induced bursal lesions and the duration of humoral immunodeficiency were examined. One-week-old specific-pathogen-free chickens were intraocularly inoculated with an intermediate vaccine strain (IBDV-Vac) or a virulent strain (IM-IBDV). At intervals postinoculation (PI), chickens were examined for histopathologic lesions. At 1, 3, 5, 10, or 15 wk PI, the chickens were injected with a mixture of antigens, and primary antibody responses were examined at 10 days postimmunization. Initially, the virus caused extensive necrosis of bursal B lymphocytes. This lesion was accompanied by an infiltration of T lymphocytes. With time, the necrotic lesion in the bursa was resolved. The follicles became partly repopulated with B lymphocytes. The repopulation occurred faster in the chickens exposed to IBDV-Vac than in the chickens exposed to IM-IBDV. By 7 wk PI, 40% and 80% of bursal follicles in IM-IBDV- and IBDV-Vac-inoculated chickens, respectively, were repopulated with immunoglobulin M+ B lymphocytes. Both IBDV-Vac and IM-caused suppression of the primary antibody response to antigens. However, the antibody responses of the chickens exposed to either of the two IBDV strains used were compromised only during the first 6 wk of virus exposure. Subsequently, the antibody response returned to near normal levels.     

Duration of immunosuppression caused by a vaccine strain of infectious bursal disease virus

The depression of response of Brucella abortus strain 19 caused by an infectious bursal disease vaccine virus given to chicks at one day old was shown to persist for four weeks. Histological examination of the bursa of Fabricius showed a gradual repopulation by bursal lymphocytes, after initial damage, concomitant with the development of a humoral response.     

鸭源新城疫病毒对鹅的致病性试验

鸭源新城疫病毒（NDV）SDFC株通过静脉注射、肌肉注射、点眼滴鼻3种途径人工感染15日龄健康雏鹅,观察试验鹅的发病情况及临床症状,于感染后不同时间剖杀,观察各组织器官的主要剖检变化,并进行病理组织学研究,同时对病毒在组织中的抗原分布进行检测。结果显示,试验鹅感染鸭源NDV后发病率达100%,静脉注射组死亡率为80%,肌肉注射组死亡率为40%,点眼滴鼻组死亡率为26.7%。病鹅表现下痢、流泪,部分出现瘫痪、扭头、角弓反张等神经症状;剖检变化表现为胰腺、脾脏有大小不等的白色坏死灶,胸腺、法氏囊萎缩,心包积液,肠道、肝脏、肺脏、肾脏出血;病理组织学变化表现为胸腺、脾脏、法氏囊等器官内淋巴细胞坏死、崩解,心脏、肺脏、肝脏、肾脏广泛性出血、变性;抗原分布检测结果显示,病毒在病鹅体内多个组织器官中分布。试验结果表明,鸭源NDV对鹅具有较强的致病性。     

鹅源新城疫病毒云南流行株免疫交叉保护试验

用分离的鹅新城疫病毒KM2007株尿囊液制成油乳剂灭活苗,和NDV油乳剂灭活苗分别接种10日龄未免疫雏鸡和未免疫雏鹅,并设非免疫对照组。免疫后21 d,试验组和对照组每只鸡和鹅分别注射0.1 mL鹅新城疫病毒KM2007株尿囊液10-1稀释液,结果对照组鹅和鸡分别出现典型的鹅新城疫和鸡新城疫的症状和病理变化,而试验组鹅和鸡全部健活。结果表明,鹅新城疫病毒KM2007株油乳剂灭活苗及NDV油乳剂灭活苗均可保护鹅和鸡免受鹅新城疫病毒野毒的攻击。     

不同来源鸡传染性法氏囊病疫苗的免疫效果观察

为了研究商品蛋雏鸡传染性法氏囊病疫苗的免疫程序,对MB株活疫苗、G606株活疫苗和B38株活疫苗3株传染性法氏囊病活疫苗进行了疫苗毒力、免疫效果及对新城疫疫苗免疫影响的观察。结果表明,MB株活疫苗毒力最强,G606株活疫苗次之,B38株活疫苗毒力最弱;突破母源抗体能力强弱依次为MB株活疫苗、G606株活疫苗、B38株活疫苗,其中B38株活疫苗产生的抗体滴度最高,MB株活疫苗次之,G606株活疫苗最低;MB株活疫苗可降低新城疫疫苗产生的血凝抑制抗体滴度,G606株活疫苗和B38株活疫苗对此无影响。     

鸡4种病毒抗原液的浓缩及其四联油佐剂灭活苗的研制

本研究通过超滤浓缩技术对鸡新城疫病毒、传染性支气管炎病毒、产蛋下降综合征病毒和传染性法氏囊病病毒的尿囊液进行了10倍或10倍以上的浓缩处理，并按一定的比例配比研制成四联油乳剂灭活疫苗，对鸡的最小免疫剂量是0.25ml，免疫接种二周后，鸡新城疫和产蛋下降综合征病毒的HI抗体效价分别达到8log     

Effect of infectious bursal disease on the response of chickens to Mycoplasma synoviae, Newcastle disease virus, and infectious bronchitis virus.

At 35 days of age, chickens which as 1-day-old chicks were inoculated with the infectious bursal disease virus (IBDV) had significantly lower antibody titers against Mycoplasma synoviae, Newcastle disease virus, and infectious bronchitis virus than did those never inoculated with IBDV. The IBDV also had a marked effect on the development of air-sac lesions. Birds infected with IBDV that were later inoculated with M synoviae (day 14), Newcastle disease virus (days 14 and 28) experienced an increased incidence and greater seversity of airsacculitis than did chicks which were not exposed to IBDV.     

Immunosuppressive effect of a highly virulent infectious bursal disease virus isolated in Japan.

The immunosuppressive effect of infectious bursal disease virus (IBDV) on vaccination against Newcastle disease (ND) was compared among 2-, 3-, and 4-week-old chickens inoculated with the highly virulent IBDV field isolate 90-11 and the reference serotype 1 strain GBF-1. In all age groups, isolate 90-11 severely suppressed antibody response to ND vaccination and protective vaccinal immunity against ND. In contrast, chickens inoculated with strain GBF-1 and vaccinated with ND vaccine were well protected from the ND virus challenge. The mitogenic response to phytohemagglutinin of splenic lymphocytes from chickens inoculated with isolate 90-11 or strain GBF-1 was significantly lower than that of uninoculated controls. There was no difference between the two inoculated groups in responsiveness, although lymphocyte depletion in the thymus was more severe in chickens inoculated with isolate 90-11 than in chickens inoculated with strain GBF-1.     

Concomitant turkey herpesvirus-infectious bursal disease vector vaccine and oil-adjuvanted inactivated Newcastle disease vaccine administration: consequences for vaccine intake and protection

Hatchery vaccination protocols in day-old chicks are designed to provide early priming and protection against several poultry diseases including, but not limited to, Marek's disease (MD), infectious bursal disease (IBD), and Newcastle disease (ND). The constraint of concomitant administration of live MD and IBD vaccines plus ND inactivated oil-adjuvanted vaccines (IOAVs) requires improvements in vaccine technology. Single-needle concomitant subcutaneous (SC) application of IBD/MDV and killed NDV vaccine and the use of viral vectors for expression of immunogenic proteins are a current trend in the industry. The objective of this work was to assess the compatibility of a turkey herpesvirus (HVT)-infectious bursal disease (vHVT-IBD) vector vaccine applied simultaneously with IOAV and to evaluate the consequences for vaccine intake, the need for additional immunizations with the respective vaccines, and protection. Five separate trials were performed using double- and/or single-needle injectors. The levels and persistence of vaccine intake, serologic response, vHVT-IBD virus combination with the MD Rispens strain, and/or live NDV vaccination were also assessed. Histopathology and PCR at injection sites showed adequate vaccine intake detected up to 44 days postvaccination. Serologic evidence of vaccine priming was observed, and all vaccinated groups differed (P < 0.05) from the control at different time points. MD, NDV, and IBD protection results after concomitant double-shot single-needle vaccination were near 85%, 95%, and 100%, respectively. Taken together the results indicate no deleterious effects on the efficacy of the vHVT-IBD vaccine monitored by vaccine intake, serologic and challenge results, and combinations after concomitant live/killed vaccination, suggesting the suitability of its use in hatchery vaccination. All types of injectors used as well as injection techniques, vaccines injected separately or together, gave the same results.     

Effects of standard and variant strains of infectious bursal disease virus on infections of chickens

T-cell-mediated and humoral immune responses were measured in chickens infected with standard and variant strains of infectious bursal disease virus. One-day-old and 3-week-old chickens were infected with these viruses and then given sheep RBC, killed Brucella abortus strain 19, and Newcastle disease virus. Appropriate serologic tests were used to monitor the primary and secondary responses to the antigens. Lymphoblast transformation assays were performed weekly. The response to the infectious bursal disease virus was determined by virus neutralization tests, microscopic examination of bursas, and bursal to body weight ratios. One-day-old chickens had T-cell-mediated and humoral immune suppression with both strains of virus, compared with controls. The lymphoblast transformation responses indicated that the variant strain was significantly (P less than 0.05) more suppressive than the standard strain. Three-week-old chickens had humoral immune suppression with the standard strain, but not with the variant strain. The lymphoblast transformation response was transiently suppressed at this age by the variant strain only. During the first week of infection, 1-day-old and 3-week-old chickens had lower neutralizing antibody titers to the variant strain than to the standard strain.     

Infectious bursal disease virus variant from commercial Leghorn pullets

An infectious bursal disease virus (IBDV) was isolated from 39-to-43-day-old commercial leghorn pullets suspected of having infectious bursal disease (IBD). These chickens had been vaccinated with a commercial live IBDV vaccine at 28 and 35 days of age. An isolate designated IN was recovered using specific-pathogen-free (SPF) chickens and the BGM-70 established cell line. Experimental studies using SPF chickens vaccinated with either inactivated vaccines made from the vaccine strain used in the problem flock or a standard-type vaccine indicated no protection against the IN isolate. However, two variants and another standard-type vaccine induced protection against the IN isolate. Cross-neutralization tests indicated that the IN isolate differed antigenically from commercial vaccine strains and was related to the variant IBDV strains recently isolated from broilers. To our knowledge, this is the first report of a variant IBDV recovered from commercial layer chickens in the United States.