Comparison of precipitin antibodies and virus-neutralizing antibodies to infectious bursal disease virus

Three hundred twenty-two serum samples from commercial pullets and multiplier breeders were analyzed for agar-gel precipitin (AGP) antibodies and virus-neutralizing (VN) antibodies to infectious bursal disease virus. Two hundred thirty-four of these sera were AGP-positive, and 88 were AGP-negative. The geometric mean of the reciprocal of the VN titers for the AGP-positive sera was 208.7, and 232 (99.1%) had a VN titer of 1:16 or greater. In contrast, the geometric mean of the reciprocal of the VN titers for the AGP-negative sera was 6.1, but 53 (60.2%) had a VN titer ranging from 1:4 to 1:256. When the AGP test was compared with the VN test, the sensitivity and specificity, respectively, of the AGP test were 81.5% and 100%.     

传染性法氏囊病病毒抗原表位分析--单克隆抗体的制备与鉴定

将传染性法氏囊病病毒(IBDV)分离毒株ZB和TA3的细胞培养物采用不连续蔗糖密度梯度离心的方法浓缩纯化病毒,免疫BALB/c小鼠,运用淋巴细胞杂交瘤技术将免疫鼠脾细胞与SP2/0骨髓瘤细胞融合,建立了6株分泌抗IBDV单克隆抗体(McAb)的杂交瘤细胞系1C1、1E6、2B2、2G8、3A2、3E2。间接ELISA测定,杂交瘤细胞培养上清液的抗体效价为102,诱生腹水的抗体效价为106～107。相加ELISA分析,这6株单克隆抗体对应不同的病毒抗原表位。中和试验结果表明,2G8对病毒有较强的中和能力,腹水的中和效价为105。用2B1和3E2配对建立的夹心ELISA可特异地检测IB DV。     

Quantitative counter-immunoelectrophoresis for estimation of antibodies to infectious bursal disease virus

Quantitative counter-immunoelectrophoresis was standardized to detect antibodies to the avian infectious bursal disease virus. This technique correlated well with the conventional quantitative agar gel precipitation test in estimating antibodies to IBDV. The use of blood dried on filter paper as an alternative to serum is discussed. QCIE is simple, easy to perform and faster than QAGP.Abbreviations AGP agar gel precipitation - CID₅₀ half-minimal chick infective dose - CIE counter-immunoelectrophoresis - EEO electroendosmosis - IBD infectious bursal disease - IBDV infectious bursal disease virus - QAGP quantitative agar gel precipitation - QCIE quantitative counter-immunoelectrophoresis     

Virus-neutralizing and passively protective monoclonal antibodies to infectious bursal disease virus of chickens.

Murine monoclonal antibodies (MAbs) were produced to assist in the identification and characterization of the virus-neutralizing epitopes of infectious bursal disease virus (IBDV). Only MAbs that reacted in Western blotting with viral protein 2 (VP2) or immunoprecipitated VP2 neutralized the infectivity of the virus in cell culture and passively protected young chickens from infection. Three of the neutralizing MAbs did not react with denatured viral proteins. Additivity enzyme-linked immunosorbent assays indicated that the six virus-neutralizing MAbs recognized two spatially independent epitopes. The ability of two of the virus-neutralizing MAbs to neutralize a variant of IBDV that had escaped neutralization by all the other MAbs confirmed the existence of two distinct neutralizing epitopes. The results support the hypothesis that there are at least two non-overlapping epitopes recognized by the virus-neutralizing MAbs reported in this study, although these may still be within one conformational site on VP2 of IBDV.     

Comparative susceptibility of chickens, turkeys and ducks to infectious bursal disease virus using immunohistochemistry

Twenty chicks, 12 turkey poults and 10 ducklings, all 5 weeks old were infected with 2 × 10^3.5 chick LD₅₀ IBD virus to determine the course of the virus in the 3 poultry species. Uninfected control birds were kept separately. Two infected and 2 control birds/species were euthanized at time intervals between 3 and 168 hours post infection (pi). Sections of thymus, bursa of Fabricius, spleen, liver, kidney, proventriculus and ceacal tonsil were stained for the detection of IBD virus antigen using immunoperoxidase technique. IBD virus antigen positive cells stained reddish-brown and the amount of such cells in tissue sections were noted and scored. Stained cells were present in all organs examined for up to 168 hours pi in the 3 poultry species except ceacal tonsils of ducks at 72 and 120 hours pi. Antigen score was highest in chickens and least in ducks as reflected by average of total scores/sampling time of 12, 10.8 and 8 in chickens, turkeys and ducks respectively. Total antigen score/sampling time in infected chickens peaked twice; 24/48 and 144 hours pi, whereas such bi-phasic peaks were absent in turkeys and ducks. Range of total antigen score at different sampling times was 7–17.5 in chickens, 10–13 in turkeys and 7–10 in ducks indicative of marked viral replication in chickens. Presence of IBD viral antigen in organs of all 3 poultry species is indicative of infections. The innate ability of turkeys and ducks to prevent appreciable replication of IBD virus after infection requires further investigation.     

Random cDNA probes to infectious bursal disease virus

Viruses from three commercially available modified-live infectious bursal disease virus vaccines were propagated in tissue culture. Following this, a series of 32P-labeled probes was generated using the entire RNA genome as template for formation of randomly primed cDNAs. These probes were tested against dot blots of the three vaccine strains, as well as the USDA standard challenge strain and one field-origin strain. Dot blots were made of both crude tissue extract and LiCl-precipitated RNA genome. All three probes detected the standard challenge and field strains. Although differences in probe binding could be quantified among the strains, cross-hybridization indicated considerable homology within genomic regions preferentially transcribed under the experimental conditions.     

鸡传染性法氏囊病病毒的快速检测

随着 IBDV变异株的出现 ,发病鸡常不产生法氏囊的肉眼病变 ,由于传染性和非传染性因素亦可引起淋巴细胞减少和法氏囊坏死 ,所以 ,采取组织病理学方法诊断 IBDV感染并不完全可靠。由于主动性抗体应答需要一定的时间及大多数雏鸡都带有母源抗体 ,因此血清学早期诊断也不完全可靠。该试验采用本所研究的 IBD快速试纸与经典的琼扩试验 ,在对 IBDV的检测效果上进行了详细的比较 ,介绍如下。1　材料与方法1 .1　 IBD快速检测试纸　由河南省农业科学院生物技术研究所制备提供。1 .2　试验鸡　 1日龄试验鸡 30 0只由河南农业大学试验鸡场提…     

Group and strain-specific neutralization sites of infectious bursal disease virus defined with monoclonal antibodies

Two somatic cell hybridizations were performed utilizing splenocytes from mice immunized with one or more strains of infectious bursal disease virus (IBDV). Supernatants from hybridoma cell lines were initially screened by the enzyme-linked immunosorbent assay (ELISA) against multiple strains of IBDV. Cell lines that secreted antibodies with ELISA reactivity patterns of interest were cloned, and their monoclonal antibodies (MCAs) were subsequently tested in cross-virus-neutralization tests. Two of the nine MCAs selected exhibited strong neutralizing activity and precipitated IBDV antigens in agar gel precipitin tests as well. MCA B69 significantly neutralized only the cloned D78 strain of IBDV, whereas MCA R63 neutralized all IBDV strains (representing both serotype I and II viruses) against which it was tested. Results of competitive ELISAs that used the R63 and B69 MCAs showed that the two neutralization sites on the D78 strain were not overlapping.     

The effect of infectious bursal disease virus on the immune system of turkeys

In 1979 it was reported that an infectious bursal disease virus (IBDV) isolated from a case of respiratory disease of turkeys differed antigenically from the chicken isolates of this virus. We injected turkey poults with the turkey-originating TY89 and chicken-originating BD/6 isolates of IBDV and studied their effects on antibody production to the virus, serum immunoglobulin G (IgG), antibody response to sheep erythrocytes, in vitro response of peripheral blood lymphocytes to mitogens, and microscopic structure of the bursa of Fabricius. The chicken isolate BD/6 caused a significant decrease in the response to sheep erythrocytes, lower serum IgG, transient decrease in the response of lymphocytes to PHA, and mild microscopic lesions in the bursa of Fabricius. The turkey isolate TY89, however, caused no obvious damage to the immune system of the infected poults. We suggest that a partial and transient functional disorder of the immune system of poults can occur after infection with IBDV originating from chickens, even if the poults exhibited no clinical signs.     

Baculovirus virions displaying infectious bursal disease virus VP2 protein protect chickens against infectious bursal disease virus infection

Infectious bursal disease (IBD) is an acute and contagious viral infection of young chickens caused by IBD virus (IBDV). The VP2 protein of IBDV is the only antigen for inducing neutralizing antibodies and protective immunity in the natural host. In the current study, we have succeeded in construction of one recombinant baculovirus BacSC-VP2 expressing His6-tagged VP2 with the baculovirus envelope protein gp64 transmembrane domain (TM) and cytoplasmic domain (CTD). The His6-tagged recombinant VP2 was expressed and anchored on the plasma membrane of Sf-9 cells, as examined by western blot and confocal microscopy. Immunogold electron microscopy demonstrated that the VP2 protein of IBDV was successfully displayed on the viral surface. Vaccination of chickens with the VP2-pseudotyped baculovirus vaccine (BacSC-VP2) elicited significantly higher levels of VP2-specific enzyme-linked immunosorbent assay antibodies and neutralizing antibodies than the control groups. IBDV-specific proliferation of lymphocytes was observed in chickens immunized with the recombinant BacSC-VP2. An in vivo challenge study of the recombinant baculovirus BacSC-VP2 showed effective protection against a very virulent (vv) IBDV infection in chickens. In addition, mortality and gross and histopathological findings in the bursa demonstrated the efficacy of the vaccine in reducing virulence of the disease. These results indicate that the recombinant baculovirus BacSC-VP2 can be a potential vaccine against IBDV infections.     

由法氏囊病毒引起鸡的免疫抑制

1法氏囊 禽类法氏囊是雏鸡免疫系统的中枢免疫器官.它是鸟类特有的免疫器官,所以值得特别关注.许多研究已搞清了其生理学作用.雏鸡前3周是法氏囊快速发展时期,在这个时期法氏囊迅速增殖,3周龄后法氏囊就逐渐退化,研究表明,大约在12周龄,法氏囊就完全退化.     

Effect of diffferent levels of maternally derived antibodies on protection against infectious bursal disease virus

Fertile eggs were obtained from three different broiler breeder flocks with different levels of virus neutralizing antibodies to infectious bursal disease virus. Egg yolk from these flocks was tested for antibody titers by the virus neutralization test. Flock I eggs had no antibodies, flock II had medium level antibodies (1:200-1600; geometric mean = 1:975), and flock III had a high level of antibodies (1:1600-6400; geometric mean = 1:3365). Chicks from the above flocks were challenged each with 10(2) 50% embryo infective dose of the IN serotype 1 variant virus at 1, 2, and 4 wk of age and examined at 5 and 11 days postchallenge. The average organ/body weight ratios were calculated and statistically analyzed. Chicks with no maternal antibodies were not protected at any age. Chicks with medium levels of maternal antibodies were protected when challenged at 1 and 2 wk of age. Chicks with high levels of maternally derived antibodies were protected when challenged at all the ages tested. The above results were statistically significant (P < 0.05).     

Failure of maternally derived infectious bursal disease antibodies to serotypes 1 and 2 to protect against heterologous virus

Chicks with maternally derived infectious bursal disease antibodies to either serotype 1 or 2 were challenged at intervals between day-old and 7 weeks of age using the homologous and the heterologous viruses. With both serotypes good protection was demonstrated against the homologous challenge, but not against the heterologous virus.