Publications

identification and comparison of point mutations associated in classic and variant infectious bursal disease viruses.	restriction enzymes (re) were used to identify point mutations in the nucleotide sequences of the infectious bursal disease virus (ibdv) strains del-e, del-a, stc, in, bursine 2, and bio-burs. the point mutations at amino acid sites 222, 254 and 323 were identified using res bstni, styi and mboi, respectively. the nucleotide sequences of stc, in, bursine 2 and bio-burs were determined at each of these sites. nucleotide sequence analysis using this data and previously reported data for del-e and ...	1997	9213387
plasma alpha 1-acid glycoprotein in chickens infected with infectious bursal disease virus.	the concentration and affinity to concanavalin a (cona) of plasma alpha 1-acid glycoprotein (agp) and agp levels in extracts of liver tissues were investigated in specific-pathogen-free chickens infected with the highly virulent hps-2 strain or virulent reference gbf-1 strain of infectious bursal disease virus. the plasma agp value in uninfected control 3- to 7-wk-old chickens was 161.8 +/- 25.8 micrograms/ml (mean +/- sd), and cona-unreactive and cona-reactive agp comprised 47% and 63% of total ...	1997	9087333
sequence comparisons of the variable vp2 region of eight infectious bursal disease virus isolates.	the vp2 gene is part of the genomic segment a of infectious bursal disease virus (ibdv). it has been identified as the major host-protective antigen of ibdv and is known to contain conformationally dependent protective epitopes. a 643-base pair segment covering the hypervariable region of this gene from three recent serologic variant ibdv isolates from the southeastern united states, two variants from the delmarva peninsula, and three serologic standard viruses were amplified and sequenced using ...	1997	9087318
three-dimensional structure of infectious bursal disease virus determined by electron cryomicroscopy.	infectious bursal disease virus (ibdv), a member of the birnaviridae group, is a commercially important pathogen of chickens. from electron micrographs of frozen, hydrated, unstained specimens, we have computed a three-dimensional map of ibdv at about 2 nm resolution. the map shows that the structure of the virus is based on a t=13 lattice and that the subunits are predominantly trimer clustered. the subunits close to the fivefold symmetry axes are at a larger radius than those close to the two- ...	1997	8985353
passive protection of specific pathogen free chicks against infectious bursal disease by in-ovo injection of semi-purified egg-yolk antiviral immunoglobulins.	in order to develop an experimental model for passive immunity in spf chickens, active neutralizing immunoglobulins (ig) directed against infectious bursal disease virus (ibdv) were extracted from the yolk of eggs laid by conventional layers immunized against ibdv. concentrated ig extracts were inoculated via the intra-vitellin route into 7-day-old embryonated spf hen eggs. although detrimental to hatchability, ig inoculation resulted in hatching two series of spf chicks with passive immunity ag ...	1997	9283288
sequence and phylogenetic analyses of highly virulent infectious bursal disease virus.	the nucleotide sequences of the genome segments a and b encoding the precursor polyprotein (nh2-vp2-vp4-vp3-cooh) and vp1 were determined for a highly virulent strain of infectious bursal disease virus (ibdv). the precursor polyprotein and vp1 coding regions of highly virulent okym strain consisted of 3039 nucleotides (1012 deduced amino acids) and 2640 nucleotides (879 deduced amino acids), respectively. comparison of the deduced amino acid sequences of the highly virulent ibdv (hv-ibdv) with o ...	1997	9267454
effects of beta-carotene and canthaxanthin on aflatoxicosis in broilers.	in 2 x 3 factorial experiments, 240 broiler chicks were fed diets containing 0, 0.01, and 0.02% beta-carotene or canthaxanthin with or without 5 ppm aflatoxin to determine the effects of these two carotenoids on the health and well-being of broilers subjected to aflatoxin poisoning. neither beta-carotene nor canthaxanthin was effective at overcoming the growth-depressing effects of aflatoxin. relative liver weights were significantly higher in broilers receiving dietary aflatoxin in the presence ...	1997	9316107
efficacy of a novel infectious bursal disease virus immune complex vaccine in broiler chickens.	two experiments were conducted to test the efficacy of a novel infectious bursal disease virus (ibdv) vaccine in broiler chickens with maternal ibdv immunity. the ibdv vaccine was formulated by mixing ibdv strain 2512 with bursal disease antibodies (bda) to produce the ibdv-bda complex vaccine. in expt. i, 1-day-old cobb x cobb broiler chickens were vaccinated subcutaneously with either ibdv-bda or commercial live intermediate ibdv vaccine (vaccine a) or were left unvaccinated. in expt. 2, the v ...	1997	9454922
detection of infectious bursal disease viruses in commercially reared chickens using the reverse transcriptase/polymerase chain reaction-restriction endonuclease assay.	bursa samples from the united states, mexico, and puerto rico were tested for the presence of infectious bursal disease virus (ibdv) using the reverse transcriptase/polymerase chain reaction-restriction endonuclease (rt/pcr-re) assay. this assay amplifies a 394-bp fragment of the ibdv vp2 gene. a total of 151 samples were tested. each was from a different physical location or farm. forty-eight of the samples were determined to contain ibdv using rt/pcr. the re profiles on 44 of these positive sa ...	1997	9087330
the 5'-terminal 32 basepairs conserved between genome segments a and b contain a major promoter element of infectious bursal disease virus.	the regions of the infectious bursal disease virus (ibdv) genome with regulatory function are not known. in the present study, progressively deleted lengths of the 5' noncoding region of segment a were constructed in pgl3 vectors having sv40 enhancer or promoter, and a luciferase (luc) reporter gene. transient transfections of the constructs made in a promoter-less pgl3-enhancer vector when transfected in vero cells and the lysates assayed for luc expression, allowed the localization of maximal ...	1997	9672609
restriction fragment length polymorphisms in the vp2 gene of infectious bursal disease viruses.	infectious bursal disease viruses (ibdvs) were examined for restriction fragment length polymorphisms in a fraction of the vp2 gene with the use of the reverse transcriptase/polymerase chain reaction-restriction fragment length polymorphism (rt/pcr-rflp) assay. the restriction enzymes bstni and mbol were used to obtain rflp results. a third enzyme, styi, was tested, but its utility for differentiation of ibdv strains was limited. thirteen vaccine viruses and five ibdv strains that were previousl ...	1997	9356709
appearance of t cells in the bursa of fabricius and cecal tonsils during the acute phase of infectious bursal disease virus infection in chickens.	groups of 3-wk-old specific-pathogen-free chickens were inoculated intraocularly with two virulent and one vaccine strain of infectious bursal disease virus (ibdv). during the acute phase of infection, the bursa of fabricius and cecal tonsil were examined by immunohistochemistry for ibdv antigen and t cell. with all three viruses examined, the infection resulted in the appearance of viral antigen in the bursa accompanied by the presence of cd3+ cells. the cd3+ cells were predominantly tcr2+ and ...	1997	9356710
applications in in ovo technology.	by mid-august 1995, 55% of broiler embryos in north america were vaccinated for marek's disease using the inovoject system, with 201 inovoject machines placed with 16 of the top 25 poultry producers, providing the industry with the capacity to inject in excess of 400 million eggs per month or about 5 billion eggs per annum. in ovo administration of a bursal disease antibody-infectious bursal disease virus (bda-ibdv) complexed vaccine to specific-pathogen-free (spf) embryos was safer and more pot ...	1997	9037703
history of infectious bursal disease in the u.s.a.--the first two decades.	infectious bursal disease (ibd) emerged in 1957 as a clinical entity responsible for acute morbidity and mortality in broilers on the delmarva peninsula. the condition spread rapidly and was recognized throughout the u.s. broiler and commercial egg production areas by 1965. early attempts to isolate the etiologic agent were impeded by a lack of specific-pathogen-free (spf) eggs and by deficiencies in viral and serologic techniques. by 1967, the highly infectious nature of the agent was recognize ...	1997	9087316
molecular identification of infectious bursal disease virus strains.	twenty-two infectious bursal disease virus (ibdv) strains were examined using the reverse transcriptase/polymerase chain reaction-restriction endonuclease (rt/pcr-re) assay. a 394-bp fragment of the vp2 gene was amplified and tested for six different restriction enzyme sites. although the ecorii enzyme was used in previous rt/pcr-re assays, results obtained using the isoschizomer bstni were more consistent because its activity does not rely on multiple restriction sites. ten different rt/pcr-re ...	1997	9087325
further development and use of a molecular serotype identification test for infectious bronchitis virus.	previously, we developed a rapid serotype identification test for infectious bronchitis virus (ibv) that utilizes the reverse transcriptase-polymerase chain reaction (rt-pcr) and restriction fragment length polymorphism analysis. the rt-pcr is used to amplify the s1 gene from rna extracted from the virus grown in eggs. restriction enzyme digestion and electrophoresis of that pcr product is used to determine the serotype of the virus. the purpose of this study was threefold. first, using a modifi ...	1997	9087326
infectious bursal disease virus: a review of molecular basis for variations in antigenicity and virulence.		1997	9114957
infectious bursal disease virus polyprotein processing does not involve cellular proteases.	the larger genome segment, segment a, of infectious bursal disease virus (ibdv) encodes vp2, vp3 and vp4 as a precursor polyprotein. the viral protease, vp4, is responsible for self-processing of the polyprotein, however, there are additional secondary precursor products such as vpx whose further processing has not been defined. expression of ibdv cdnas in vitro with rabbit reticulocyte lysates in a coupled transcription-translation system and in the sindbis virus expression system (with bhk-21 ...	1997	9672603
antigenic and s-1 genomic characterization of the delaware variant serotype of infectious bronchitis virus.	a previously unrecognized infectious bronchitis virus (ibv) serotype, referred to hereafter as the delaware variant (de var), was isolated from commercial broiler chickens during a severe, widespread respiratory disease epornitic in the delmarva peninsula region of the united states in january-march 1992. the de var serotype was found to be antigenically unrelated by virus-neutralization (vn) test to nine reference ibv serotypes from north america. additional vn tests indicated that the de var i ...	1997	9356713
quantitative competitive polymerase chain reaction for detection and quantification of infectious bursal disease virus cdna and rna.	a polymerase chain reaction (pcr)-based method to measure complementary dna (cdna) and rna levels of infectious bursal disease virus (ibdv) was developed. quantification was achieved by quantitative competitive pcr (qc-pcr) amplification. a competitor, a deletion mutant of the wild type ibdv cdna, was 10-fold serially diluted and co-amplified with ibdv cdna after being reversely transcribed from the viral rna. after agarose gel electrophoresis, staining, and densitometric scanning, the bands on ...	1997	9220388
national surveillance of poultry diseases in lebanon.	from 1992 to mid-1996, a national survey of poultry diseases in lebanon was conducted. this surveillance included meat breeder, layer breeder, commercial layer and chicken broiler flocks. the history, signs, lesions and laboratory tests of poultry were used in the diagnosis of prevalent poultry diseases. culture techniques were used to screen for bacterial diseases; serological techniques and, to a lesser extent, culture techniques were used to diagnose viral diseases; and both serological and c ...	1997	9567302
limited antigenic variation among recent infectious bursal disease virus isolates from france.	seven neutralizing monoclonal antibodies (mabs) to infectious bursal disease virus (ibdv) were used in an antigen-capture elisa for the antigenic characterization of 58 ibdv isolates obtained in france since 1989. fifty-six isolates exhibited an antigenic profile which was different from reference strain faragher 52/70, and similar to french very virulent ibdv strain 89,163 (no binding of two mabs). two strains (3.4%), isolated in 1991 and 1994, showed additional antigenic modifications resultin ...	1997	9413517
a second form of infectious bursal disease virus-associated tubule contains vp4.	preparations of density gradient-purified infectious bursal disease virus (ibdv) were found to contain full and empty icosahedral virions, type i tubules with a diameter of about 60 nm, and type ii tubules 24 to 26 nm in diameter. by immunoelectron microscopy we demonstrate that virions and both types of tubular structures specifically react with anti-ibdv serum. in infected cells intracytoplasmic and intranuclear type ii tubules reacted exclusively with an anti-vp4 monoclonal antibody, as did t ...	1997	9343252
systemic and local antibody responses to infectious bronchitis virus in chickens inoculated with infectious bursal disease virus and control chickens.	serum and local (respiratory) antibody responses to infectious bronchitis virus (ibv) were studied in 5-wk-old white leghorn-type control chickens and chickens inoculated with infectious bursal disease virus (ibdv) at 1 day of age. of the chickens inoculated with ibv alone, 93% had detectable levels of ibv antibodies in the sera and 87% had detectable antibodies in the respiratory lavage fluids. compared to this group, only 73% and 65% of ibdv-ibv inoculated chickens had serum and respiratory an ...	1997	9356695
the major antigenic protein of infectious bursal disease virus, vp2, is an apoptotic inducer.	infectious bursal disease virus (ibdv) is the causative agent of an economically important poultry disease. vaccinia virus recombinants expressing the ibdv mature structural capsid proteins vp2 and vp3 were generated by using vectors for inducible gene expression. characterization of these recombinant viruses demonstrated that expression of vp2 leads to induction of apoptosis in a variety of mammalian cell lines. transfection of cell cultures with a expression vector containing the vp2 coding re ...	1997	9311897
viral diseases of the immune system and strategies to control infectious bursal disease by vaccination.	viral infections which are immunosuppressive can affect the economics of poultry production, often as a result of the chicken's increased susceptibility to secondary infections and sub-optimal response to vaccinations. the mechanism of this immunosuppression has been studied in detail for certain chicken viruses. the replicating virus can have both direct and indirect effects on the cells of the immune system. the special role of the bursa of fabricius, as a lympho-epithelial organ, will be ment ...	1997	9276986
evidence that virion-associated vp1 of avibirnaviruses contains viral rna sequences.	the vp1 encoded by genomic segment b of birnaviruses is generally known to exist as a genome-linked protein (vpg) and as a "free" polypeptide of 90 kda in virus particles. the guanylylation activity associated with infectious bursal disease virus (ibdv) was demonstrated by incubating purified virus in presence of [alpha 32p] gtp; optimum activity in the 90 kda form of vp1 was seen in low salt concentration in the presence of 4 mm magnesium ions over a wide range of incubation temperatures. the i ...	1997	9229010
myeloperoxidase activity in chicken heterophils and adherent cells.	chicken heterophils are known to lack myeloperoxidase (mpo) activity. in this paper, evidence is presented to show that chicken heterophils and adherent cells contain a dna sequence that is homologous to segment 10 of the human mpo gene; histochemical staining and microplate assay also show that heterophils and adherent cells contain mpo activity.	1997	9261969
comparison of the in situ changes in lymphoid cells during infection with infectious bursal disease virus in chickens of different ages.	in situ immunocytochemical staining was used to characterise leukocyte changes and determine tropism of infectious bursal disease virus following infection of neonate and 3-week-old chickens. in the bursae of both groups, massive replication of the virus, a rapid depletion of b cells and an influx of cd4(+) tcr-alphabeta(1)(+) and cd8 (+) tcr-alphabeta(1)(+) cells was detected within 4 days post-inoculation. leukocyte changes in the spleen, thymus and harderian gland were similar in both groups. ...	1997	18483946
histopathology and immunohistochemistry of renal lesions due to avian infectious bronchitis virus in chicks uninoculated and previously inoculated with highly virulent infectious bursal disease virus.	a nephropathogenic strain of infectious bronchitis virus (ibv) was inoculated intra-tracheally into 14-day-old specific-pathogen-free chicks or ones previously inoculated with highly virulent infectious bursal disease virus (ibdv) at 7 days of age. the renal lesions were examined histopathologically and immunohistochemi-cally at intervals up to 30 days post-inoculation. the mortality was 20% in the ibdv + ibv-inoculated group, but not in the ibv-inoculated one. swollen and pale kidneys due to ib ...	1997	18483931
cytotoxic activity of cells recovered from the respiratory tracts of chickens inoculated with infectious bronchitis virus.	previously uninoculated control chickens and chickens exposed to infectious bursal disease virus (ibdv) at 1 day of age were intranasally exposed to the m41 strain of infectious bronchitis virus (ibv) at 5 wk of age. between 7 and 13 days after inoculation with ibv, cells were collected from the respiratory tracts of both groups of chickens and assayed for in vitro cytotoxic activity against a lymphoblastoid lscc-rp9 target cell line using a 4-hr 51chromium-release assay (cra). compared to thymo ...	1997	9356717
expression of md infectious bursal disease viral proteins in baculovirus.	genomic segment a of the variant infectious bursal disease virus (ibdv) strain md was amplified by reverse transcriptase/polymerase chain reaction and further characterized by baculovirus expression. three different baculovirus clones were constructed containing the genes encoding vp2, vp2/vp4, and the complete polyprotein cloned into the baculovirus transfer vector pvl1392. baculovirus recombinants were identified by dot blot hybridization and were plaque purified three times. baculovirus expre ...	1997	9356708
some characteristics of a cellular receptor for virulent infectious bursal disease virus by using flow cytometry.	a flow cytometric virus binding assay that directly visualizes the binding of infectious bursal disease virus (ibdv) to its target cells was established. the chicken b lymphoblastoid cell line, lscc-bk3, which is permissive for ibdv infection, bound high levels of the virus. another b lymphoblastoid cell line, lscc-1104-b1, bound low levels of the virus, although it was nonpermissive. no virus binding was detected in nonpermissive t lymphoblastoid cell lines. in the binding assay to heterogeneou ...	1998	9930190
immunorheophoresis for the diagnosis of infectious bursal disease.	the immunorheophoresis (ir) technique was used for the detection of infectious bursal disease antigen from bursae collected from field cases and experimentally infected chickens. when these results were compared with that of the agar gel immunodiffusion (agid) test, they showed excellent agreement as determined by kappa value. however, the time taken for the appearance of the precipitin lines was reduced from 14-24 hr in the agid test to 3-5 hr in the ir technique.	1998	9645332
genetic heterogeneity in the vp2 gene of infectious bursal disease viruses detected in commercially reared chickens.	the genetic heterogeneity of infectious bursal disease virus (ibdv) vaccine strains was compared with ibdv detected in bursa tissue of commercially reared chickens. the vaccine strains tested represented classic viruses from the united states, south africa, england, and france plus variant viruses from the united states. bursa tissue samples used for the detection of ibdv from commercially reared chickens were from the united states. genetic heterogeneity was examined using restriction fragment ...	1998	9645324
molecular characterization of seven chinese isolates of infectious bursal disease virus: classical, very virulent, and variant strains.	seven infectious bursal disease virus (ibdv) strains isolated from china have been characterized in this study, including a classical strain cj801, an attenuated strain gz911, a variant strain gz902, and four very virulent strains g9201, g9302, f9502, and hk46. with the use of reverse transcription-polymerase chain reaction, the full-length vp2 genes were amplified and the hypervariable regions were sequenced. protein sequences of the hypervariable region (a.a. 143-382) of the field isolates con ...	1998	9645325
western blot detection of infectious bursal disease virus infection.	in order to evaluate the use of a western blot methodology for the diagnosis of infectious bursal disease virus (ibdv) infection, chickens were experimentally infected with ibdv strains and tested for the presence of viral antigens and antibodies by a blocking western blot test (bwb). the viral proteins obtained from the bursa of fabricius (bf) were transferred to a nitrocellulose membrane after sodium dodecyl sulfate-polyacrylamide gel electrophoresis (sds-page), and the chicken sera obtained b ...	1998	9698773
[comparative analysis of the vp2 variable region of the gene from infectious bursal disease virus isolates].	variable cdna regions in the vp2 gene of 24 isolates of infectious bursal disease virus (ibdv) isolated in russia in 1993-1996 were amplified by the "nested" pcr and sequenced. the primary structure analysis of the vp2 gene variable region revealed 2 major groups of ibdv isolates. the first group consisted of the isolates with the structure identical or closely related to the highly virulent european strains cs89, 74/89a, 661, jy86, and dv86, the second group included the isolates with a high le ...	1998	9511141
protection of broiler breeders by an inactivated combined water-in-oil-in-water viral vaccine.	a four-component vaccine, prepared by combining the single vaccines, contains subunits of newcastle disease and infectious bronchitis viruses, as well as whole inactivated infectious bursal disease and egg drop syndrome viruses. the vaccine is prepared in the form of a low-viscosity water-in-oil-in-water emulsion with low mineral oil content. heavy breeders were vaccinated at the age of 20 weeks by intramuscular administration of 0.5 ml vaccine/bird in an experiment carried out under field condi ...	1998	9704508
enhanced expression of cytokine genes in spleen macrophages during acute infection with infectious bursal disease virus in chickens.	we examined the effects of infectious bursal disease virus (ibdv) on splenic t cells and macrophages. in acute ibdv infection, splenocytes responded poorly to con a stimulation. however, when t cells were isolated from whole spleen cells, purified t cells responded normally to con a. this result indicated that functional t cells were present in the spleen but mitogen-induced proliferation of t cells was being suppressed by other cells. previous studies indicated that soluble factors from suppres ...	1998	9613445
immunopotentiating effects of azadirachta indica (neem) dry leaves powder in broilers, naturally infected with ibd virus.	effects of feeding of powdered dry leaves of a. indica (ai) were investigated on humoral and cell mediated immune responses, in a flock of broilers which had survived an outbreak of infectious bursal disease (ibd). ai (2 g/kg) treatment significantly enhanced the antibody titres against new castle disease virus (ncdv) antigen and also potentiated the inflammatory reactions to 1. chloro-2,4-di- nitro benzene (dncb) inskin contact test. the results indicate that ai could be beneficial in immunosup ...	1998	10085786
coding region of segment a sequence of a very virulent isolate of ibdv--comparison with isolates from different countries and virulence.	we determined the sequence of the coding region of segment a, coding for the viral proteins (vps) vp2, vp4, and vp3, of a very virulent (vv) infectious bursal disease virus (ibdv) isolated in israel and named ibdvks. we compared the deduced amino acid sequences of the proteins of the new isolate with those of the same proteins from several ibdv isolates, as published in recent years. the amino acid sequences of vp3 and vp4 of the israeli isolate were 1.9%-2.3% different from the sequences of the ...	1998	9777150
critical amino acid changes in vp2 variable domain are associated with typical and atypical antigenicity in very virulent infectious bursal disease viruses.	classical serotype 1 infectious bursal disease viruses (ibdv), but not very virulent (vv) isolates, react with neutralizing monoclonal antibody (nmab) 3 in virus neutralization tests or antigen-capture elisa. two other nmabs, 6 and 8, bind to both classical and most vv strains, but not to the atypical 94,432 and 91,168 vv strains, respectively. the basis for such reactivities was investigated by sequencing the genome region encoding the vp2 major immunogenic domain. in classical, variant, vaccin ...	1998	9739340
generation of infectious pancreatic necrosis virus from cloned cdna.	we developed a reverse genetics system for infectious pancreatic necrosis virus (ipnv), a prototype virus of the birnaviridae family, with the use of plus-stranded rna transcripts derived from cloned cdna. full-length cdna clones of the ipnv genome that contained the entire coding and noncoding regions of rna segments a and b were constructed. segment a encodes a 106-kda precursor protein which is cleaved to yield mature vp2, nonstructural protease, and vp3 proteins, whereas segment b encodes th ...	1998	9765436
alteration of chicken heterophil and macrophage functions by the infectious bursal disease virus.	the effects of the infectious bursal disease virus (ibdv) on chicken heterophils and macrophages are reported. short-term incubation of ibdv with heterophils causes an activation of cellular oxidative burst, a decrease in phagocytosis and cellular migration, and an increase in cellular adherence to the ibdv-infected chicken embryo fibroblasts. under electron microscopic examination, heterophils show condensed chromatin and packets of intact granules, either free or being phagocytized by macropha ...	1998	9790874
restriction fragment length polymorphism analysis of highly virulent strains of infectious bursal disease viruses from holland, turkey, and taiwan.	strains of highly virulent infectious bursal disease virus (hvibdv) from turkey (oa, oe), holland (hol), and taiwan (pt, il) were characterized by reverse transcriptase/polymerase chain reaction-restriction fragment length polymorphism (rt/pcr-rflp) analysis and compared with the united states of america (usa) classic (stc) and variant (md, in) serotype 1 viruses and serotype 2 oh strain. a primer pair that amplified a 743-bp fragment of the vp2 gene was used. the rflp profiles of the rt/pcr pro ...	1998	9777147
the working mechanism of an immune complex vaccine that protects chickens against infectious bursal disease.	the role of immune complexes (icx) in b-cell memory formation and affinity maturation allow for their potential use as vaccines. recently, a new immune complex vaccine has been developed that is currently under field trials conducted in commercial poultry. this immune complex vaccine is developed by mixing live intermediate plus infectious bursal disease virus (ibdv) with hyperimmune ibdv chicken serum (ibdv-icx vaccine). here we have investigated the infectivity of this vaccine as well as the n ...	1998	9824516
sequence analysis of the vp2 hypervariable region of nine infectious bursal disease virus isolates from mainland china.	the vp2 hypervariable region of infectious bursal disease virus (ibdv) from nine mainland chinese strains was amplified by reverse transcriptase/nested polymerase chain reaction and cloned into pgem-t vector. the nine isolates, which were from the center (hn3), the north (bj-1, b2/28, hd96), the east (js-18 and ah-2), the northeast (d11-2, c4-2), and the west (ts) of china, were sequenced and compared with each other and with six reference ibdv sequences. clustering analysis separated the nine i ...	1998	9876846
simplified sample processing combined with a sensitive nested polymerase chain reaction assay for detection of infectious bursal disease virus in the bursa of fabricus.	a rapid and sensitive protocol for the detection and amplification of infectious bursal disease virus (ibdv) rna in the bursa of fabricius was developed. by digestion with proteinase k and subsequent extraction with phenol and chloroform, ibdv rna was efficiently released from a single bursa. ibdv rna extraction time was shortened to 4 hr, compared with 24 hr with the traditional method, and only one bursa was needed instead of five. this more simplified procedure resulted in a significant reduc ...	1998	9777148
heat inactivation of serotype 1 infectious bursal disease virus.	heat inactivation curves for infectious bursal disease virus serotype 1 (ibdv) strain 52/70 in bursal homogenate supernatant were constructed for 70 degrees c, 75 degrees c and 80 degrees c. biphasic, multiple kinetics curves were produced with an initial rapid drop in infectivity followed by a more gradual decline. in this second phase the approximate times taken to reduce the infectivity by 1 log(10) at each temperature were: 70 degrees c (18.8 min), 75 degrees c (11.4 min) and 80 degrees c (3 ...	1998	18483970
comparative study of the resistance or susceptibility of local nigerian and exotic chickens to infectious bursal disease.	local or village chickens are the major source of poultry products in less developed countries, but information is limited on their susceptibility or resistance to diseases. in this work, 6-week-old local nigerian chickens, pullets and broilers were used. one day before infection the mean body weight of the broilers was more than twice that of the pullets and local chickens. the bursa: body weight (b:bw) indices of the pullets and local chickens were similar, but were significantly higher than t ...	1998	18483982
inflammatory response of different chicken lines and b haplotypes to infection with infectious bursal disease virus.	chickens representing two different inbred lines (layer and meat-type) and three different b haplotypes (bw1, b19 and b131) were infected with infectious bursal disease virus (ibdv) at 21 days of age. mortality was recorded, and surviving chickens were killed and examined either 3 or 17 days post-infection. non-infected control chickens were run in parallel. the variables recorded were all significantly changed by the virus infection, including the serum concentration of mannan-binding lectin th ...	1998	18483984
a double antibody sandwich elisa for rapid diagnosis of virus infection and to measure the humoral response against infectious bursal disease on clinical material.	a double antibody sandwich elisa (das-elisa) was developed and employed for simultaneous direct detection of infectious bursal disease virus (ibdv) from bursal samples and to measure the humoral response, using the same basic immunoreagents. the purified and non-purified antigen, capture antibody and chicken hyperimmune sera were prepared, and standardized for this purpose. the das-elisa was applied to both 80 bursal suspensions and 224 corresponding serum samples from vaccinated and non-vaccina ...	1998	18484029
in-situ apoptosis in chickens infected with infectious bursal disease virus.	groups of specific pathogen-free chickens aged 3 weeks were inoculated with one of three strains of infectious bursal disease virus (ibdv), namely: (1) a classical virulent strain, im-ibdv; (2) an antigenic variant-e strain, ve-ibdv; and (3) an attenuated vaccine strain, b2-ibdv. the bursa of fabricius and thymus were examined 1 to 5 days after inoculation for histopathological lesions, ibdv antigen, and in-situ apoptosis. infection of chickens with im-, ve-, or b2-ibdv resulted in the appearanc ...	1998	9500235
penguin mystery.		1998	9578772
expression of orf a1 of infectious bursal disease virus results in the formation of virus-like particles.	a recombinant vaccinia virus inducibly expressing orf a1 of infectious bursal disease virus (ibdv) has been constructed and characterized. cells infected with this recombinant virus express the ibdv polyprotein, which is proteolytically processed to give mature vp2, vp3, and vp4 polypeptides. an electron microscopy study revealed that the cytoplasm of cells infected with the recombinant virus contains abundant ibdv-like particles (vlp). these vlp form close-packed paracrystalline arrays that are ...	1998	9603319
identification and characterization of rna-binding activities of avian reovirus non-structural protein sigmans.	cytoplasmic extracts prepared from avian reovirus (arv) strain s1133-infected chicken embryo fibroblasts were examined for the presence of rna-binding proteins in order to identify and characterize arv rna-binding proteins. analysis of binding activity to poly(a)-sepharose indicated that infected cells contained significant amounts of a protein that co-migrated with arv protein sigmans present in total virus-infected cell extracts. determination of the n-terminal amino acid sequence of several p ...	1998	9634083
rapid preparation of plasma membranes from avian lymphoid cells and fibroblasts for virus binding studies.	a simple and rapid protocol for the preparation of plasma membranes from chicken embryo fibroblasts and chicken lymphoid cells was developed. characterization of the preparations by morphological, biochemical and serological methods indicated the specific enrichment of the plasma membranes as well as cell surface proteins. binding of infectious bursal disease virus (ibdv) particles was demonstrated after immobilization of the plasma membranes, and cell type-specific differences were observed. al ...	1998	9694323
detection of infectious bursal disease virus of poultry in clinical samples by rt-pcr.	the rt-pcr technique was adopted to amplify variable region of vp2 gene of infectious bursal disease virus using three different sets of primers. these primers could generate products of 643, 474 and 552 bp sizes. the authenticity of the amplicons was confirmed by their size in agarose gel, restriction enzyme digestion and by nested pcr. out of total five clinical samples tested, ibd viral genomic rna could be detected in four by rt-pcr. restriction enzyme digestion of pcr products with stui cou ...	1998	9678252
antigenic and immunogenic properties of baculovirus-expressed infectious bursal disease viral proteins.	genomic segment a of the variant md infectious bursal disease virus (ibdv) was amplified by reverse transcriptase/polymerase chain reaction, cloned, and expressed in the baculovirus expression system. three different baculovirus recombinants expressing the genes encoding vp2, vp2/vp4, and the complete polyprotein (vp2/vp4/vp3) were prepared. the three antigens were used in separate enzyme-linked immunosorbent assays, and each detected antibodies against the variant ibdv strains md, del-a, del-e, ...	1998	9533084
infectious bursal disease virus changes the potassium current properties of chicken embryo fibroblasts.	infectious bursal disease virus (ibdv) is the causative agent of an economically significant poultry disease. ibdv infection leads to apoptosis in chicken embryos and cell cultures. since changes in cellular ion fluxes during apoptosis have been reported, we investigated the membrane ion currents of chicken embryo fibroblasts (cefs) inoculated with the cu-1 strain of ibdv using the patch-clamp recording technique. incubation of cefs with ibdv led to marked changes in their k+ outward current pro ...	1998	9657954
a novel technique for in-vivo assay of viral regulatory regions in genomes of animal rna viruses.	a novel in-vivo assay system for mapping and analyzing regulatory signals which promote transcription and expression of viral rna genomes is described. the system was developed using infectious bursal disease virus (ibdv), a double-stranded rna virus and vero cells which are permissive for ibdv, as a model. the model system consisted of engineered modifications of an enhancer-less pgl3-promoter vector such that deleted lengths of the 5' noncoding region of genome segment a of ibdv were positione ...	1998	9672132
biochemical and hormonal changes associated with experimental infection of chicks with infectious bursal disease virus.	the inoculation of chicks with the infectious bursal disease (ibd) virus manifested typical clinical signs indicative of ibd viral infection. the inoculated birds seroconverted and showed significantly decreased total protein, lipid and a decrease in the albumin to globulin ratio. a significant increase was seen in the concentration of corticosterone and thyroxine but not in the triiodothyronine level.	1998	9852766
seroprevalence of infectious bursal disease virus in free-living wild birds in japan.	serum samples collected from 739 free-living wild birds of 44 species from gifu, mie and hyogo prefectures in japan during the period 1989 to 1997 were tested for antibodies to infectious bursal disease virus (ibdv) serotypes 1 and 2 by a virus neutralization test. serological evidence of infection with serotypes 1 and 2 was found in 15 (2%) of the sera of 6 species and 36 (4.9%) of the sera of 11 species, respectively. antibodies to ibdv were detected from both sedentary and migratory species. ...	1998	9853315
infectious bronchitis virus antibodies in tears and their relationship to immunity.	antibodies to infectious bronchitis virus (ibv) in chicken tears were investigated to determine if they could be used as an indicator of protective immunity. antibody production in tears and serum was measured by enzyme-linked immunosorbent assay (elisa) in specific-pathogen-free (spf) white leghorn and broiler chickens vaccinated with a live attenuated vaccine containing the massachusetts (mass) connaught strain of ibv. the effect of virulent infectious bursal disease virus (ibdv) infection on ...	1998	9645328
effect of immunostimulation on cytotoxic activity of intestinal intraepithelial lymphocytes of chickens in infectious bursal disease and eimeria tenella infections.	in chickens, intestinal intraepithelial lymphocytes (iiels) exhibit spontaneous natural killer (nk) cell like activity, by which they are active in the first line of defence on gut epithelial linings. in the present study, the cytotoxic activity of iiels was found to be drastically suppressed in chickens experimentally infected with infectious bursal disease (ibd) virus at the age of 5 weeks and also in chickens experimentally infected with eimeria tenella oocysts at the age of 8 weeks (p < 0.01 ...	1998	9704505
[gumboro vaccination].		1998	9537067
infectious bursal disease and hemorrhagic enteritis.	infectious bursal disease (ibd) of chickens and hemorrhagic enteritis (he) of turkeys are caused by infectious bursal disease virus (ibdv) and hemorrhagic enteritis virus (hev), respectively. both diseases have common features, including an acute stage followed by immunosuppression, resulting in lowered resistance to a variety of infectious agents and poor response to commonly used vaccines. the ibdv and hev infections are widespread in commercial chicken and turkey flocks, respectively. the acu ...	1998	9706087
poultry industry strategies for control of immunosuppressive diseases.	immunosuppression has historically cost the poultry industry in increased mortality and in performance factors during rearing. in addition, immunosuppression has had a negative impact on the ability of the poultry industry to process chickens due to associated health problems. industry strategies for controlling immunosuppression are not consistent between broiler companies. the broiler industry is refining their strategies for controlling immunosuppression based on research and field observatio ...	1998	9706089
immunohistochemical investigation of the tissue distribution of mannan-binding lectin in non-infected and virus-infected chickens.	this paper describes the results of immuno-histochemical staining for chicken mannan-binding lectin (mbl) in formalin-fixed tissue sections from non-infected chickens, and from chickens infected with infectious laryngotracheitis virus (iltv) or infectious bursal disease virus (ibdv). in the non-infected chickens, mbl was detected in the cytoplasm of a few hepatocytes and in the germinal centres of the caecal tonsils, whereas sections of kidney, heart muscle, spleen, cerebrum, thymus, adrenal gla ...	1998	9708196
humoral and cell-mediated immunopotentiation in vaccinated chicken layers by thymic hormones and zinc.	the humoral and cell-mediated immunities to a trivalent killed vaccine, administered subcutaneously to white leghorn-chicken layers at 29 and 31 weeks of age, and containing antigens of infectious bronchitis virus (ibv), infectious bursal disease virus (ibdv), and newcastle disease virus (ndv), were quantitated in five vaccinated and one unvaccinated-control group. four out of the five vaccinated groups were immunopotentiated by various combinations of zinc and thymic hormones administered intra ...	1998	9713942
pathogenicity and immunosuppressive properties of infectious bursal disease virus field isolates and commercial vaccines in india.	the pathogenicity and immunosuppressive properties of two field isolates of infectious bursal disease. virus (ibdv) and five commercial ibdv live virus vaccines marketed in india were evaluated in this study. the pathogenicity of the wild type viruses and vaccines were based on mortality, the bursa:body weight ratio and microscopic lesions in the bursa in 3-week-old chicks that received these viruses. the immunosuppressive effects of these viruses were evaluated by measuring the antibody respons ...	1998	9719845
study of leg weakness in two commercial broiler flocks.	the major causes of leg weakness/lameness were investigated in two male commercial broiler flocks. the numbers of dead and lame birds culled from the flocks each day were recorded by the flock managers. forty-four lame birds and 22 sound birds were examined postmortem during a period of six weeks and the proximal and distal end of each femur, tibiotarsus and tarsometatarsus were examined histologically. attempts were made to isolate bacteria and viruses from the proximal end of each femur. blood ...	1998	9725184
research notes: elispot assay for detection of antibody secreting cells to infectious bursal disease virus in chickens.	the elispot assay was used to enumerate antibody secreting cells (asc) in spleens of chickens infected with infectious bursal disease virus (ibdv). in the first experiment, chickens were orally challenged with ibdv. spleens were collected 14 d later and used for elispot assay. the assay detected 16 to 28 igg asc per 10(6) splenocytes and 3 to 6 igm asc per 10(6) splenocytes. in the second experiment, chickens were vaccinated against ibdv and orally challenged with ibdv 14 d after vaccination. sp ...	1998	9603352
preliminary report of a controlled trial of mth-68/b virus vaccine treatment in acute b and c hepatitis: a phase ii study.	eighty four patients with viral hepatitis attributed to infection with hepatitis b virus (hbv) (n = 43) or hepatitis c virus (hcv) (n = 41) were included in this study employing the mth-68/b vaccine, an attenuated variant of bursal disease virus. twenty of the 43 patients in the hbv group, and 22 of the 41 hcv patients were treated with mth-68/b. the remaining patients received conventional therapy. significantly more patients progressed into active chronic hepatitis on conventional therapy (13% ...	1998	9615801
a comparison of two rna isolation methods for double-stranded rna of infectious bursal disease virus.	infectious bursal disease virus (ibdv), a member of the birnaviridae family, contains a bisegmented double-stranded rna (dsrna) genome. the segments are linked covalently at 5' termini by a large (90 kda) viral genomic protein that migrates similar to viral rna dependent rna polymerase of ibdv. a proteinase k digestion based approach and acid-guanidium-phenol-chloroform (agpc) rna extraction method were used to extract dsrna of ibdv from infected bursae. after extraction, dsrna of ibdv was purif ...	1998	9779617
genetic resistance to avian viruses.	viral infections of poultry can be catastrophic in terms of both welfare and economics, and although vaccines have been very successful in combating these diseases, new forms of viruses have evolved which present increasing difficulties for vaccine control. differences in genetic susceptibility are known to exist for many of the major viral pathogens of poultry. consequently, an increase in the level of genetic resistance provides a possible means of enhancing protection of flocks. this is parti ...	1998	9638814
fluorescence spectroscopy monitoring of the conformational restraint of formaldehyde- and glutaraldehyde-treated infectious bursal disease virus proteins.	interaction of native proteinaceous antigens during the recognition and the effector phases of an immune response leads to antigenic conformational modifications which may elicit additional specific immune response. protein cross-linking and conformation restraining formaldehyde and glutaraldehyde have been extensively used in vaccine preparation, but the relative efficiencies of conformational restraint at concentrations similar to those used in vaccine preparation have not been investigated. w ...	1998	9796050
fowl adenovirus recombinant expressing vp2 of infectious bursal disease virus induces protective immunity against bursal disease.	the right hand end nde i fragment 3 (90.8-100 map units) of the fowl adenovirus serotype 10 (fav-10) was characterised so as to allow the location of an insertion site for recombinant vector construction. infectious bursal disease virus (ibdv) vp2 gene from the australian classical strain 002/73, under the control of the fav-10 major late promoter/leader sequence (mlp/ls) was inserted into a unique not i site that was generated at 99.5 map units. this recombinant virus was produced without delet ...	1998	9645198
generation of a mutant infectious bursal disease virus that does not cause bursal lesions.	a reverse genetics system for birnavirus, based on synthetic transcripts of the infectious bursal disease virus (ibdv) genome, was recently developed (e. mundt and v. n. vakharia, proc. natl. acad. sci. usa 93:11131-11136, 1996). to study the function of the 17-kda nonstructural (ns) protein in viral growth and pathogenesis, we constructed a cdna clone of ibdv segment a in which the first and only initiation codon (atg) of ns protein was mutated to a stop codon (tag). transfection of vero cells ...	1998	9525581
formation of virus-like particles when the polyprotein gene (segment a) of infectious bursal disease virus is expressed in insect cells.	the baculovirus expression vector system was used to examine the expression of the full-length infectious bursal disease virus (ibdv) segment a cdna, which encodes the structural proteins in a polyprotein precursor that is autocatalytically cleaved to vpx, vp3, and vp4. no vp2 was observed in lysates of recombinant baculovirus infected cells indicating the lack of processing of vpx to vp2 in this system. virus-like particles (vlp) were purified from the infected insect cells, and on negative sta ...	1999	9918334
susceptibility of local nigerian and exotic chickens to infectious bursal disease by contact exposure.	one hundred 6-week-old susceptible cockerels were inoculated with a pathogenic strain of infectious bursal disease virus (ibdv) and kept in the same pen as 100 each of 6-week-old pullets, local chickens and broilers. the cockerels developed depression and diarrhoea on day 3 post inoculation (pi) and most of the pullets and some of the local chickens and broilers showed similar signs on day 4 pi. loss in weight was severe and similar in the pullets and local chickens, being significantly greater ...	1999	10371006
protection of chickens against very virulent infectious bursal disease virus (ibdv) and marek's disease virus (mdv) with a recombinant mdv expressing ibdv vp2.	to develop a herpes virus vaccine that can induce immunity for an extended period, a recombinant marek's disease (md) virus (mdv) cvi-988 strain expressing infectious bursal disease virus (ibdv) host-protective antigen vp2 at the us2 site (rmdv) was developed under the control of an sv40 early promoter. chickens vaccinated with the rmdv showed no clinical signs and no mortality and 55% of the chickens were considered protected histopathologically after challenge with very virulent ibdv (vvibdv), ...	1999	10329546
sequence analysis of australian infectious bursal disease viruses.		1999	10197249
successful treatment of decompensated chronic viral hepatitis by bursal disease virus vaccine.	three cases of women with chronic liver inflammation caused by hepatitis b (two) and c (one) viral infections, were followed up to twelve years after diagnosis. as conventional therapy was ineffective and the patients progressed into decompensated liver disease, they were superinfected with massive doses of an attenuated variant (mth-68/b) of the apathogenic avian bursal disease virus (a double-stranded rna virus from the birnaviridae family). clinical symptoms and biochemical abnormalities were ...	1999	10216467
induction of protective immunity in chickens immunised with plasmid dna encoding infectious bursal disease virus antigens.	direct dna inoculations were used to determine the efficacy of gene immunisation of chickens to elicit protective immune responses against infectious bursal disease virus (ibdv). the vp2 gene of ibdv strains gp40 and d78, and the vp2-vp4-vp3 encoding segment of strain d78 were cloned in an expression vector which consisted of human cytomegalovirus (hcmv) immediate early enhancer and promoter, adenovirus tripartite leader sequences and sv40 polyadenylation signal. for purification of vaccine-qual ...	1999	10641338
serum levels of chicken mannan-binding lectin (mbl) during virus infections; indication that chicken mbl is an acute phase reactant.	mannan-binding lectin (mbl) is a serum collectin which is believed to be an opsonin of the innate immune defence against various microorganisms. mbl is a minor acute phase reactant in man. we investigated the concentration of serum mbl in chickens infected with infectious bronchitis virus (ibv) and infectious laryngotracheitis virus (iltv). the concentration of serum mbl increased about twofold (from approximately 6 to 12 microg/ml) due to these viral infections. the concentration peaked 3-7 day ...	1999	10507370
amplification and cloning of infectious bursal disease virus genomic rna segments by long and accurate pcr.	improved methods of reverse transcription, polymerase chain reaction (pcr) amplification, and cloning of full-length coding region of both strands of infectious bursal disease virus (ibdv) variant strain e genome were developed. denaturation of ibdv rna by heat in the presence of primers and use of a reverse transcriptase lacking rnase-h activity produced full-length coding region and partial non-coding region cdna copies of the viral genomic segments. digestion of the rna component of rna-cdna ...	1999	10507413
[gumboro vaccine].		1999	10549091
poultry vaccines: an analysis of the animal trials required for vaccine testing and the way to reduce or refine these tests.	the testing of vaccines for use in chickens requires a large number of animal trials. especially for poultry vaccines, quality testing of each batch consists of testing for extraneous agents in chickens for all products and potency tests for inactivated products. for the licensing of a vaccine a number of safety and efficacy tests is necessary. the safety testing covers dose and overdose studies, and the influence on reproductive performances and immunological functions. for live vaccines some a ...	1999	10566779
storage of viruses on filter paper for genetic analysis.	the purpose of this study was to develop a method to store viruses on filter paper without the need for special conditions for future use of the genetic material. two non-enveloped viruses were used as models. infectious bursal disease virus (ibdv), a double-stranded rna virus that infects chickens, belongs to the birnaviridae family. hemorrhagic enteritis virus (hev), with double-stranded dna, belongs to the adenoviridae family. three different solutions were found suitable for loading the viru ...	1999	10598079
persistent infection with chicken anaemia virus and some effects of highly virulent infectious bursal disease virus infection on its persistency.	chicken anaemia virus (cav) infectivity and the effect of highly virulent infectious bursal disease virus (hv ibdv) infection on cav's infectivity were examined in chickens inoculated with cav or inoculated dually with cav and hv ibdv. five chickens inoculated dually with hv ibdv at 35 days old and then with cav at 40 days old exhibited no clinical signs of disease, but showed atrophic bursae of fabricius when necropsied 4 weeks later. upon examining the chickens at 7 days postinoculation (dpi) ...	1999	10607503
proteolytic processing in infectious bursal disease virus: identification of the polyprotein cleavage sites by site-directed mutagenesis.	the infectious bursal disease virus (ibdv), a member of the birnaviridae family, is the causative agent of an immune depressive disease that affects domesticated and wild avian species. the expression strategy of ibdv includes the synthesis of a 110-kda polyprotein containing the capsid precursor polypeptides. the polyprotein is autocatalitically processed rendering three polypeptides: nh2-vpx-vp4-vp3-cooh. we have carried out a systematic analysis, using a series of plasmids encoding polyprotei ...	1999	10489352
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 inj ...	1999	10494408
a ribozyme targeted to rna polymerase gene of infectious bursal disease virus effectively cleaves and inhibits expression of the viral gene product.	five hammerhead-type ribozymes were designed and cloned to cleave infectious bursal disease virus (ibdv) rna and inhibit protein synthesis from cloned full-length viral cdna genes. two ribozymes (r1 and r2) were directed to the large viral rna segment gene and three ribozymes (r3, r4, and r5) were directed to the small viral rna segment gene. targets for the ribozymes were produced from cloned full-length coding regions of both small and large viral rna segment genes. ribozymes and their corresp ...	1999	10825922
viral protein 1 sequence analysis of three infectious bursal disease virus strains: a very virulent virus, its attenuated form, and an attenuated vaccine.	comparisons between sequences of very virulent, virulent, and attenuated strains of the infectious bursal disease virus (ibdv) may indicate sites on the genome co-inciding with virulence. in an attempt to detect if such sites exist on the coding region of segment b, viral protein 1 (vp1) (encoded for by segment b) of a very virulent israeli virus, il3; its attenuated strain, il4; and the attenuated winterfield vaccine 2512 were cloned and sequenced. a comparison was made among them and with six ...	1999	10216760
organ culture of chicken bursa as a model to study the pathogenicity of infectious bursal disease virus isolates.	in vitro study with chicken bursal organ culture was attempted to assess the pathogenicity of locally isolated infectious bursal disease virus (ibdv) initially isolated from the bursa of naturally infected birds. in bursal organ culture, lymphoblastic transformation was noticed as early as 24 hr postinoculation and reached maximum at 72 hr postinoculation. the other microscopic changes were increased number of macrophages and formation of plasma cells. the ibdv antigen was detected 24 hr onward ...	1999	10396628
antigenic and molecular characterization of three infectious bursal disease virus field isolates.	three infectious bursal disease field viruses, identified as u28, 3212, and miss and isolated in the early 1980s from the southeastern united states, were characterized both antigenically and genotypically. a panel of monoclonal antibodies (mabs) was utilized in an antigen-capture enzyme-linked immunosorbent assay (elisa) for antigenic characterization. the elisa data indicated that u28 and the delaware variants are antigenically related. the 3212 and the gls variants were more closely related a ...	1999	10396632
chimeric infectious bursal disease virus-like particles expressed in insect cells and purified by immobilized metal affinity chromatography.	chimeric virus-like particles (vlps) of infectious bursal disease virus (ibdv) were produced by coinfecting spodoptera frugiperda (sf-9) insect cells with two recombinant baculoviruses, vibd-7 and vedlh-22. vibd-7 encodes vp2, vp3, and vp4 of the ibdv structural proteins. vedlh-22 encodes vp2 with five histidine residues at the carboxy-terminus (vp2h). coinfection produced hybrid vlps composed of vp2, vp2h, and vp3. the additional histidine residues on vp2h enabled the efficient purification of ...	1999	10397829
effect of thymus extract on immunologic reactivity of chicken vaccinated with infectious bursal disease virus.	the effects of crude thymus extract on the immune response and protection against challenge with virulent infectious bursal disease virus (ibdv) were studied in one-day-old chick. oral administration of thymus extract (1 ml/kg) markedly and significantly increased the total protein, albumin, globulin, tri-iodothyronine (t3), thyroxine (t4) and the body weight gain in one-day-old chick. in addition, it increased the total lymphocytic count over four weeks after administration. although vaccinatio ...	1999	10458105