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herpesvirus of turkey recombinant viruses expressing infectious bursal disease virus (ibdv) vp2 immunogen induce protection against an ibdv virulent challenge in chickens.two recombinant herpesviruses of turkey (hvt) expressing the vp2 protein of infectious bursal disease virus (ibdv or gumboro disease virus) have been constructed: vhvt001 and vhvt002. the vp2 open reading frame was inserted at the locus of the small subunit of ribonucleotide reductase gene (hsv-1 ul40 homolog) without any exogenous promoter in vhvt001 and at the locus of gl gene (hsv-1 us7 homolog) under the control of the human cytomegalovirus immediate-early promoter in vhvt002. the isolation ...19957645252
detection of infectious bursal disease virus by reverse transcription-polymerase chain reaction amplification of the virus segment a gene.a reverse transcription-polymerase chain reaction (rt-pcr) amplification assay was developed to detect infectious bursal disease virus (ibdv) gene sequences in clinical samples, infected cell cultures and chicken embryos. two pairs of primers were designed to amplify the 5'- and 3'-termini of segment a genes that partially code for the ibdv proteins vp2 and vp3, respectively. one primer pair specifies a 309-bp fragment, the other a 520-bp fragment. direct rt-pcr analysis of 5 bursal samples of c ...19957673388
the pathogenesis of infectious bursal disease: serologic, histopathologic, and clinical chemical observations.infectious bursal disease in 35-day-old specific-pathogen-free (spf) chickens was characterized clinically by its acute onset and brief duration. clinical signs included depression, anorexia, diarrhea, and polyuria. a detectable precipitin antibody response occurred between 3 and 5 days postinoculation. evaluation of pooled serum samples obtained from infectious bursal disease virus (ibdv)-infected chickens revealed transient changes in potassium, cholesterol, uric acid, lactate dehydrogenase, s ...19836316894
applications of the polymerase chain reaction to detect infectious bursal disease virus in naturally infected chickens.reverse transcriptase-polymerase chain reaction was used for identification of israeli isolates of infectious bursal disease virus (ibdv). the system was applied to tissue culture and to bursa of fabricius from infected chickens; these latter samples had been frozen for as long as 4 years. from base homology analysis of published sequences of serotype 1 ibdv, two pairs of primers, targeted to amplify sequences from the vp2 and vp3 cistrons, were prepared. the two sets of primers could detect vir ...19947702524
immune responses of breeding chickens to trivalent oil emulsion vaccines: responses to infectious bronchitis.three similar flocks of broiler breeder parent chickens that had been given live infections bronchitis (ib) vaccines during rearing were injected at 20 weeks of age with three different oil emulsion vaccines: a commercial monovalent newcastle disease (nd) vaccine (flock a); an experimental bivalent vaccine containing nd and infectious bursal disease (ibd) components (flock b); and an experimental trivalent vaccine containing nd, ibd and ib components (flock c). one week after vaccination 40 hens ...19816266125
subclinical infectious bursal disease in commercial broiler flocks in saskatchewan.five commercial broiler flocks, not vaccinated for infectious bursal disease virus, derived from infectious bursal disease virus-vaccinated breeder flocks were surveyed for evidence of bursal damage and infectious bursal disease virus infection. they were compared with two groups of birds raised in isolation. serum samples from one day old chicks contained maternal anti-infectious bursal disease virus antibodies which declined to undetectable levels by four weeks of age. serum antibody levels re ...19816268263
active cross-protection induced by a recombinant baculovirus expressing chimeric infectious bursal disease virus structural proteins.the vp2 structural gene encoded in the large genomic segment a of the variant gls strain of infectious bursal disease virus (ibdv) was modified to encode a neutralization epitope (b69), found only on classic strains of ibdv. a chimeric cdna clone of the large segment a, encoding vp3, vp4, and the modified variant ibdv vp2 structural proteins, was expressed in a recombinant baculovirus. the chimeric protein expressed was assessed with a panel of neutralizing monoclonal antibodies (mabs), and it c ...19947702501
direct correlation between the titer of infectious bursal disease virus vp2-specific antibody and protection.the titer of antibody specific to infectious bursal disease virus (ibdv) was measured by a new method and correlated with protection. challenge was carried out in chickens with various antibody titers, which were measured using a latex agglutination-inhibition (li) test, a rapid and easy technique for measuring ibdv vp2-specific antibody. when actively immunized chickens had li titers of 1:2 or more, almost all were protected from subsequent challenge with highly virulent ibdv. in contrast, even ...19947980272
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 v ...19816279066
an outbreak of infectious bursal disease among chickens between 16 and 20 weeks old.infectious bursal disease (ibd) was diagnosed in a flock of 1,031 broilers and cockerels aged between 16 and 20 weeks. affected birds passed whitish, watery feces. on postmortem examination, the bursa of fabricius (bursa) was enlarged and the kidney tubules were well distended. histopathological sections of the bursa were characterized by edema, destruction of lymphocytes, and heterophilic infiltration. spread was rapid, and the average mortality rate was 3.5%. bursal homogenates from dead chick ...19816279063
antibody detection in matched chicken sera and egg-yolk samples by commercial enzyme-linked immunosorbent assay kits for newcastle disease virus, infectious bronchitis virus, infectious bursal disease virus, and avian reovirus.elisa kits have been used to detect antibody in egg yolk. the major advantage eggs offer over blood samples is the ability to collect samples without compromising flock biosecurity. a disadvantage to using egg yolk over sera concerns the method of preparing yolk for antibody testing. the technique used in this study involved a simple dilution method with no mixing or extraction. to determine the adequacy of yolk samples to replace serum samples, a serum sample and the first six eggs were obtaine ...19938257378
rapid and quantitative assay system for measuring anti-infectious bursal disease virus antibody using monoclonal antibody bound to polystyrene latex microspheres.a monoclonal antibody (mab) to infectious bursal disease virus (ibdv) that has virus-neutralizing activity was bound to polystyrene latex microspheres the microspheres agglutinated with extracts of bursae from chickens infected with ibdv. agglutination was inhibited in a competitive manner by adding serum obtained from ibdv-infected chickens. the level of agglutination-inhibition depended on the serum antibody titer against ibdv. the reaction was visually accomplished within 5 minutes. the titer ...19938257372
detection of genetic variations in serotype i isolates of infectious bursal disease virus using polymerase chain reaction and restriction endonuclease analysis.reverse transcription with polymerase chain reaction (pcr) followed by restriction endonuclease analysis detected genetic variations among serotype i isolates of infectious bursal disease virus (ibdv). using a set of synthetic primers derived from the large genome segment of aphis-ibdv, the hypervariable region (acci-spei fragment) located in the vp2 gene was amplified. with all strains, a cdna fragment of approximately 643 bp was amplified, indicating that there were no apparent deletions or in ...19947989444
enzyme-linked immunosorbent assay-based detection of antibodies to antigenic subtypes of infectious bursal disease viruses of chickens.an enzyme-linked immunosorbent assay (elisa) using a fragment of the infectious bursal disease virus (ibdv) vp2 gene expressed in baculovirus was developed. a 944-bp portion of the vp2 gene from the del-a strain of ibdv was ligated into the pac360 transfer vector and transfected into baculovirus, recombinant baculoviruses were identified by dot blot hybridization. the recombinant baculovirus 9a5 expressed a 57-kda vp2 fusion protein, which was immunoprecipitated. this baculovirus-expressed vp2 w ...19968807213
genetic differences in susceptibility of chicken lines to infection with infectious bursal disease virus.mortality rates in 11 inbred and partially inbred chicken lines inoculated with a very virulent strain (cs89) of infectious bursal disease virus (ibdv) varied considerably, being highest (almost 80%) in a brown leghorn line (brl). bursa of fabricius to body weight ratios were depressed in the survivors in each line, but no differences were observed between lines. however, histological examination of bursae from survivors showed that, although bursal damage occurred in every line, it was most sev ...19938385328
epitope mapping of capsid proteins vp2 and vp3 of infectious bursal disease virus.twenty hybridoma cell lines producing monoclonal antibodies (mabs) against serotype 1 infectious bursal disease virus (ibdv) of gbf-1 and the attenuated gbf-1e strains were produced. the mabs recognized major structural proteins vp2 and vp3. mab recognition sites were mapped using recombinant escherichia coli clones which expressed n-terminal and (or) c-terminal truncated virus antigens, and competitive-binding assays. at least 3 conformation-dependent serotype 1 specific virus neutralizing anti ...19968856029
pathogenicity, attenuation, and immunogenicity of infectious bursal disease virus.an investigation was conducted in specific-pathogen-free chickens on the pathogenicity of bursa-derived and tissue culture-attenuated classic (stc) and variant (in) serotype 1 strains of infectious bursal disease virus. the in bursa-derived virus caused bursal inflammation, necrosis, and atrophy earlier than the bursa-derived stc virus. both viruses lost their pathogenicity after four passages in bgm-70 cells. a statistically significant level (p < 0.05) of protection was observed in spf chicken ...19968883785
influence of the host system on the pathogenicity, immunogenicity, and antigenicity of infectious bursal disease virus.the effect of the host system on the pathogenicity, immunogenicity, and antigenicity of infectious bursal disease virus (ibdv) was investigated. one classic (sal) and one variant strain (in) of ibdv were passaged separately six times in three host systems, namely bgm-70 continuous cell line, primary chicken embryo fibroblast (cef) cells, or embryonating chicken eggs (embryos) or one time in the bursa of fabricius (bf) of specific-pathogen-free (spf) chickens. passage in bgm-70 cells or cef cells ...19968883783
divergent antibody responses to vaccines and divergent body weights of chicken lines selected for high and low humoral responsiveness to sheep red blood cells.primary and secondary antibody responses to intramuscularly administered proteins of eschericia coli (f11), newcastle disease virus (ncd), infectious bronchitis virus (ib), and infectious bursal disease virus (ibd), respectively, were measured at weekly intervals in two chicken lines. the latter had been divergently selected for high and low antibody responses to sheep red blood cells (srbc), and in a random-bred control line. an oil-based adjuvant was required to induce primary and secondary an ...19968883795
replacement of challenge procedures in the evaluation of poultry vaccines.vaccination of poultry flocks, especially parent flocks, is often performed with the intention of protecting the progeny via maternal antibodies during the first weeks of life. the efficacy of this vaccination schedule, more precisely described as induction of indirect protection, is normally proven by challenging the chickens. to avoid the challenge, some trials were performed, with the intention of establishing a correlation between antibody titres of vaccinated hens, embryonated eggs, and hat ...19968785945
the effect of route of inoculation on protection by killed vaccines in chickens.the effect of various routes of immunization on protection against challenge by virulent agents was examined in chickens. chickens were immunized intratracheally, intranasally, per os, by crop gavage, and intramuscularly. agents examined were killed haemophilus paragallinarum, mycoplasma gallisepticum, and infectious bursal disease virus. results of immunization by intratracheal administration were equivalent to those produced by parenteral administration. all vaccines effectively induced produc ...19958561734
reverse passive haemagglutination test in the diagnosis of infectious bursal disease.the reverse passive haemagglutination test (rpha) was used to detect infectious bursal disease (ibd) virus antigen in various organs of experimentally infected chickens and field cases. the results of rpha were compared with those of agar gel immunodiffusion (agid) and latex agglutination (lat) tests. ibd antigen was detected in 86.4%, 80.4% and 80.5% of different organs by rhpa, lat and agid respectively. although the differences are not statistically significant, the lat is recommended because ...19957770951
concomitant ornithobacterium rhinotracheale and newcastle disease infection in broilers in south africa.ornithobacterium rhinotracheale was first isolated from broilers in south africa in 1991. the importance of o. rhinotracheale infections has been established, with growth suppression, respiratory symptoms, and arthritis commonly seen as complications. dual infection with newcastle disease and o. rhinotracheale in 28-day-old broilers led to more severe respiratory lesions and higher mortality rates than in birds with only newcastle disease. it was concluded that the pathogenicity of newcastle dis ...19968790906
monitoring of highly virulent infectious bursal disease in botswana 1989 to 1993. 19947809988
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.19947831758
immunogenic activity of viral polypeptides of an indian isolate of infectious bursal disease virus.an indian isolate of infectious bursal disease virus, i.e. ibdv-p/ad/81, was analysed for immunogenic activity of its structural polypeptides. virus was purified from infected bursal homogenate by sucrose density gradient centrifugation. it showed five different structural polypeptides of 75.8, 45, 40.7, 33.1 and 27 kda molecular weights in sodium dodecyl sulphate polyacrylamide gel electrophoresis (sds-page). anti infectious bursal disease virus (ibdv) antibodies were tested using enzyme-linked ...19947821977
diseases and management of backyard chicken flocks in chitungwiza, zimbabwe.to gather information on backyard chicken flocks in chitungwiza, an urban center in zimbabwe, 85 flock owners were interviewed. the mean flock size was 53 birds (range 1-650), and most birds were kept for meat, for either domestic consumption or local sale. mean age at slaughter was 12.4 weeks (range 8-24). none of the owners vaccinated their birds, and reported mortality rates were high (mean 25%), most commonly being associated with diseases causing eye and respiratory problems. most owners co ...19947832719
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 ...19979276986
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 ...19979267454
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 ...19979356717
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 ...19979316107
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 ...19989500235
a rapid quantitative method for detecting infectious bursal disease virus using polystyrene latex microspheres.a monoclonal antibody (mab) to infectious bursal disease virus (ibdv) was bound to polystyrene latex microspheres. the microspheres agglutinated with extracts of bursae and sera from chickens infected with all strains or isolates of ibdv tested. agglutination appeared within a 10-min reaction time. the assay could detect a 10(3.7) to 10(4.5) mean embryo infective dose (eid50) of the virus in 0.01 ml and the titer of the assay was 10- to 40-times higher than that of the agar gel precipitin test.19938395538
[gumboro vaccination]. 19989537067
sequence comparisons of a highly virulent infectious bursal disease virus prevalent in japan.variable cdna regions in the vp2 gene of five highly virulent infectious bursal disease viruses (ibdvs) isolated in japan were amplified by polymerase chain reaction (pcr) and sequenced. the nucleotide sequences of five highly virulent ibdvs were identical. comparisons of the nucleotide and the deduced amino acid sequences with those of other strains of ibdv indicated that japanese highly virulent ibdv is different from all other strains of ibdv that were compared. the number of amino acids that ...19938395796
determination of optimum formulation of a novel infectious bursal disease virus (ibdv) vaccine constructed by mixing bursal disease antibody with ibdv.a novel vaccine against infectious bursal disease virus (ibdv) has been developed. the new vaccine was constructed by mixing bursal disease antibody (bda) contained in whole antiserum with live ibdv before lyophilization. to establish various formulations of bda and ibdv, several bda doses between 5 units and 80 units of bda/50 microliters were mixed with 100 eid50/50 microliters of ibdv suspension in expt. 1; in expt. 2, several ibdv doses between 10 eid50/50 microliters and 977 eid50/50 microl ...19958719201
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 ...19989613445
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 ...19989678252
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 ...19989706089
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 ...19999918334
the culture of chicken embryo fibroblast cells on microcarriers to produce infectious bursal disease virus.the cultures of chicken embryo fibroblast (cef) cells in flasks, spinner bottles, and bioreactors were studied. the growth and metabolism characteristics of cef cells and the feasibility of the cef cell culture in bioreactor were investigated. the plating process of the cef cells on gt-2 microcarriers in spinner bottles was studied, and a plating kinetic model was presented. the culture of cef cells in 1.5 l celligen bioreactor to produce infectious bursal disease virus (ibdv) had met success. w ...19979170258
coagglutination test for rapid detection of infectious bursal disease virus antigen. 19979203312
sequence analysis of australian infectious bursal disease viruses. 199910197249
self-assembly of the infectious bursal disease virus capsid protein, rvp2, expressed in insect cells and purification of immunogenic chimeric rvp2h particles by immobilized metal-ion affinity chromatography.a gene encoding a structural protein (vp2) of a local strain (p3009) of infectious bursal disease virus (ibdv) was cloned and expressed using the baculovirus expression system to develop a subunit vaccine against ibdv infection in taiwan. the expressed rvp2 proteins formed particles of approximately 20-30 nm in diameter. those particles were partially purified employing sucrose density gradient ultracentrifugation, and the purified particles were recognized by a monoclonal antibody against the v ...200010581441
generation of full-length cdna of the two genomic dsrna segments of infectious bursal disease virus.to determine the complete nucleotide sequence of infectious bursal disease virus (ibdv) isolates, an efficient method was developed to generate full-length cdna of both the genomic a- and b-segments. reverse transcription was carried out at the highest possible temperature (50 degrees c) for the reverse transcriptase enzyme, and the single stranded cdna was subsequently amplified by using an optimized pcr. the double stranded, full-length cdna was efficiently cloned into a high copy number plasm ...200010644086
chimeras in noncoding regions between serotypes i and ii of segment a of infectious bursal disease virus are viable and show pathogenic phenotype in chickens.two serotypes, i and ii, have been identified for infectious bursal disease virus (ibdv), a member of the family birnaviridae: here, the generation by reverse genetics of ibdv chimeras in segment a of the bisegmented genome is reported. the 5- and 3'-noncoding regions (ncrs) of a serotype ii strain were exchanged with the ncrs of a full-length cdna clone of segment a of a serotype i strain. isolated chimeric viruses were characterized in cell culture and susceptible chickens. the results show th ...200010644853
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.19979261969
antigenic properties and diagnostic potential of baculovirus-expressed infectious bursal disease virus proteins vpx and vp3.the routine technique for detecting antibodies specific to infectious bursal disease virus (ibdv) is a serological evaluation by enzyme-linked immunosorbent assay (elisa) with preparations of whole virions as the antigens. to avoid using complete virus in the standard technique, we have developed two new antigens through the expression of the vpx and vp3 genes in insect cells. vpx and especially vp3 were expressed at high levels in insect cells and simple to purify. the immunogenicity of both pr ...200010882666
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 ...199910396628
filter paper technique for seromonitoring against infectious bursal disease. 19947900225
measuring infectious bursal disease virus rna in blood by multiplex real-time quantitative rt-pcr.a quantitative reverse transcription polymerase chain reaction (rt-pcr) protocol for assessing infectious bursal disease virus (ibdv) rna levels in blood was developed using the abi prism 7700 sequence detection system coupled with taqman chemistry. to control for variations in sampling and processing between samples 28s rrna was co-amplified in a multiplex reaction and used to quantify total rna. relative quantification and standardisation was achieved using a log10 dilution series of rna extra ...200010716338
ibdv-induced bursal t lymphocytes inhibit mitogenic response of normal splenocytes.we examined the suppressive activity of bursal t cells induced by infectious bursal disease virus (ibdv) in inbred (15x7) and outbred commercial specific-pathogen-free (spf) chickens. the suppressive activity was measured by the ability of bursal and splenic t cells from ibdv-infected chickens to inhibit mitogenic responses of normal splenocytes. the bursacytes but not the splenocytes of ibdv-infected chickens inhibited the mitogenic responses of normal splenocytes. the mitogenic inhibition by t ...200010760389
rescue of very virulent and mosaic infectious bursal disease virus from cloned cdna: vp2 is not the sole determinant of the very virulent phenotype.many recent outbreaks of infectious bursal disease in commercial chicken flocks worldwide are due to the spread of very virulent strains of infectious bursal disease virus (vvibdv). the molecular determinants for the enhanced virulence of vvibdv compared to classical ibdv are unknown. the lack of a reverse genetics system to rescue vvibdv from its cloned cdna hampers the identification and study of these determinants. in this report we describe, for the first time, the rescue of vvibdv from its ...200010888607
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 ...19989657954
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.19989852766
rocket immunoelectrophoresis in the diagnosis of infectious bursal disease.the rocket immunoelectrophoresis (rie) test was used for the qualitative detection and quantitative estimation of infectious bursal disease virus (ibdv) specific antigen in experimentally infected chickens and samples collected from suspected outbreaks. the ibdv specific antigen was detected in the bursae of experimentally inoculated chickens up to 5 days post infection (pi) by the agar gel precipitation (agp) test and 7 days pi by the rie test. the rie detected ibdv specific antigen in a signif ...200010907288
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 ...19989930190
vp5, the nonstructural polypeptide of infectious bursal disease virus, accumulates within the host plasma membrane and induces cell lysis.infectious bursal disease virus (ibdv) encodes a 17-kda nonstructural polypeptide known as vp5. this polypeptide is not essential for virus replication in vitro but it plays an important role in in vivo dissemination and pathogenesis. we have characterized the expression of vp5 in three eukaryotic systems: (i) ibdv-infected chicken embryo fibroblasts; (ii) bsc-1 cells infected with a recombinant vaccinia virus vector; and (iii) cos-1 cells transiently transfected with a plasmid vector. immunoflu ...200011080482
[workshop: immunosuppression in chickens]. 200111194506
lysis of myelocytes in chickens infected with infectious bursal disease virus.in specific-pathogen-free chickens infected with the highly virulent hps-2 strain or virulent reference gbf-1 strain of infectious bursal disease virus (ibdv), pathologic changes of the bone marrow were investigated. on histologic examination, bone marrow lesions were prominent in the hps-2 group but only mild in the gbf-1 group. the bone marrow of the hps-2 group showed severe lysis and depletion of heterophil myelocytes with pyknotic nuclear alteration 2-3 days after inoculation. on examinatio ...199910098643
in situ localization of infectious bursal disease virus-binding cells by a biotin-streptavidin system.a biotin-streptavidin system was established to directly visualize infectious bursal disease virus (ibdv)-binding cells in cell culture or in fresh tissues. the cells or tissue sections were first incubated with a biotinylated, purified ibdv strain gz911 and then with a streptavidin-beta-galactosidase conjugate. in the presence of the enzyme substrate x-gal, ibdv-binding cells were labeled in blue color. by applying this method to frozen tissue sections, virus-binding sites were localized in sit ...200111417836
antibody titers to infectious bursal disease virus in broiler chicks after vaccination at one day of age with infectious bursal disease virus and marek's disease virus.the effect of day-of-age vaccination with infectious bursal disease virus (ibdv) alone or in combination with marek's disease virus (mdv) in broiler chicks was investigated. one-day-old commercial broiler progeny obtained from ibdv-immunized breeder flocks were vaccinated subcutaneously according to the manufacturer's directions with live-attenuated commercially available vaccines as follows: ibdv alone, mdv alone, ibdv + mdv, and unvaccinated control. ibdv was not detected after vaccination by ...200011195642
recombinant semliki forest virus vector exhibits potential for avian virus vaccine development.the semliki forest virus (sfv) expression system was evaluated as a basis for avian vaccine development. initial studies indicated that 1-day-old specific pathogen-free (spf) chicks were susceptible to infection with an infectious strain of sfv, producing sfv-specific antibodies but no clinical disease. one-day-old spf chicks immunised intramuscularly with recombinant replication-defective sfv (rsfv) particles expressing the escherichia coli (e. coli) lacz reporter gene developed high titres of ...200111312006
the in vivo and in vitro effects of chicken interferon alpha on infectious bursal disease virus and newcastle disease virus infection.the in vitro and in vivo effects of chicken interferon alpha on infectious bursal disease virus (ibdv) infection were investigated in this study. a cdna of interferon alpha was first cloned from a chinese strain chicken shiqi by reverse transcription-polymerase chain reaction. the deduced amino acid sequence has one amino acid substitution with chicken interferon alpha 1 at residue 65 (n to s) and two amino acid substitutions with chicken interferon alpha 2 at residues 50 (n to s) and 58 (p to l ...200111417818
alteration of amino acids in vp2 of very virulent infectious bursal disease virus results in tissue culture adaptation and attenuation in chickens.reverse genetics technology offers the possibility to study the influence of particular amino acids of infectious bursal disease virus (ibdv) on adaptation to tissue culture. genomic segments a and b of the very virulent (vv) ibdv field strain uk661 were completely cloned and sequenced, and the strain was rescued from full-length cdna copies of both segments (uk661rev). using site-directed mutagenesis, alteration of a single amino acid in the segment a-encoded vp2 (a284t) resulted in a limited c ...200211752708
one-step rt-pcr for the detection of infectious bursal disease virus in clinical samples.a single-tube, non-interrupted, one-step rt-pcr has been standardized to amplify the hypervariable region of the vp2 gene sequence of infectious bursal disease virus (ibdv). the technique standardized on purified viral rna was successfully applied to the detection of the virus directly in clinical samples. the amplified products were confirmed to be ibdv specific by their size in ethidium bromide-stained agarose gel, nested pcr and restriction enzyme digestion. digestion of the amplicons with st ...200111469514
molecular characterization of seven field isolates of infectious bursal disease virus obtained from commercial broiler chickens.specific-pathogen-free sentinel birds were used as an initial biological system to isolate infectious bursal disease virus (ibdv) field isolates from commercial broiler farms exhibiting recurrent respiratory problems and poor performance. reverse transcription (rt)-polymerase chain reaction (pcr) was used to amplify a 248-bp product encompassing the hypervariable region of the ibdv vp2 gene. restriction fragment length polymorphism (rflp) analysis of the rt-pcr products was performed with the re ...200111569735
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 ...199910641338
dna-mediated vaccination against infectious bursal disease in chickens.the objective of the present study was to investigate the feasibility of a dna vaccine to protect chickens against infectious bursal disease virus (ibdv) infection. a plasmid dna carrying vp2, vp4, and vp3 genes of the standard challenge (stc) strain of ibdv was constructed and designated as pcr3.1-vp243-stc. one-day-old chickens were intramuscularly injected with the plasmid pcr3.1-vp243-stc once (group d1), twice (group d2), or three times (group d3) at weekly intervals. chickens at 3 weeks ol ...200111672894
antigenic and molecular characterization of recent infectious bursal disease virus isolates in china.eleven infectious bursal disease virus (ibdv) strains isolated recently from china were compared with the early classical virulent strain cj801, the chicken embryo fibroblast-adapted (cef) variant strain gz902, and the attenuated vaccine strains bj836, bk912, and lm to discern the evolutionary characteristics of ibdv in china at both antigenic and genetic levels. virus neutralization (vn) assay showed that all ten very virulent (vv) ibdv strains belong to the same subtype as attenuated strains, ...200212018704
proliferation of lung macrophages in acute fatal viral infections in chickens.marked proliferation of macrophages engulfing yellow pigments and fragmented erythrocytes were seen in the air capillaries and blood capillaries of the lungs of chickens affected with acute fatal viral hydropericardium syndrome, highly pathogenic infectious bursal disease, and highly pathogenic avian influenza. proliferation of lung macrophages was associated with systemic proliferation of macrophages. acute destruction of erythrocytes in these infections may have induced systemic hyperplasia of ...200111785886
efficacy and safety of an infectious bursal disease virus intermediate vaccine in ovo.the study was divided into two experiments. in the first experiment, the efficacy of in ovo intermediate vaccine against infectious bursal disease virus (ibdv) was determined by challenge at 21 days of age with virulent ibdv in specific-pathogen-free (spf) and commercial chickens. this vaccine was able to induce active immunity and to protect spf chickens to challenge; protection was not complete in commercial chickens, as testified by bursal lesions, bursal index after challenge, and vaccine im ...200111785875
major histocompatibility complex-linked immune response of young chickens vaccinated with an attenuated live infectious bursal disease virus vaccine followed by an infection.the influence of the mhc on infectious bursal disease virus (ibdv) vaccine response in chickens was investigated in three different chicken lines containing four different mhc haplotypes. two mhc haplotypes were present in all three lines with one haplotype (b19) shared between the lines. line 1 further contains the bw1 haplotype isolated from a red jungle fowl. line 131 further contains the b131 haplotype isolated from a meat-type chicken. finally, line 21 further contains the international b21 ...200212033414
significance of infectious bursal disease serology in an integrated quality control program under european epidemiologic conditions.in this study performed between 1993 and 1997, infectious bursal disease virus (ibdv) antibody titers and performance data were recorded in a vertically integrated monitoring scheme in order to make a follow-up from day-old parents down to the broilers at slaughter. all measured data were used two by two in a simple correlation study to calculate the degree to which they were linearly correlated. it appeared that high and/or uniform antibody titers in the parents were correlated with increased d ...200011007008
detection of cell membrane proteins that interact with virulent infectious bursal disease virus.to detect the molecules that interact with infectious bursal disease virus (ibdv), the chicken b lymphoblastoid cell line, lscc-bk3, which is permissive for virulent ibdv infection was investigated. the sodium dodecyl sulfate-solubilized plasma membrane fraction from the cells was subjected to a virus overlay protein binding assay. the ibdv specifically bound to proteins in lscc-bk3 plasma membranes with molecular weights of 70, 82 and 110 kda. this is the first report to demonstrate cellular mo ...200111258466
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 ...199910598079
[gumboro vaccine]. 199910549091
comparison of a putative second serotype of chicken infectious anemia virus with a prototypical isolate i. pathogenesis.ciav-7 is a virus with similar pathogenic and physicochemical characteristics to, but antigenically distinct from, chicken infectious anemia virus (ciav). the pathogenesis of ciav-7 was evaluated in a comparative study with a representative isolate of ciav, the del-ros strain. the pathogenesis of ciav-7 was similar to del-ros on the basis of the clinical disease induced and gross and microscopic lesions, although ciav-7 produced fewer and less severe lesions overall. a second comparative pathoge ...200212495056
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 ...199910494408
molecular typing of infectious bursal disease virus of israeli field and vaccine strains by the reverse transcription/polymerase chain reaction/restriction fragment length polymorphism assay.infectious bursal disease viruses (ibdvs) were examined by testing bursa samples from 37 commercially reared chicken flocks and three vaccine strains by the reverse transcription (rt)/polymerase chain reaction (pcr)/restriction fragment length polymorphism assay (rflp). the assay was conducted with a 717-bp fragment of the vp2 gene with the restriction enzymes bstni and mboi. the presence of a restriction site for sspi was used to predict a very virulent phenotype. results indicated the existenc ...200111332486
tissue culture infectivity of different strains of infectious bursal disease virus is determined by distinct amino acids in vp2.two types of strains of serotype i of infectious bursal disease virus (ibdv) have been described, on the basis of their ability (ibdv-tc) or inability (ibdv-bu) to infect chicken embryonic cells in culture. however, both types infect b lymphocytes in the bursa of fabricius of young chickens. to determine the molecular basis for tissue culture infectivity, virus recombinants with chimeric segments a were constructed from ibdv-tc and ibdv-bu by reverse genetics. the region responsible for the diff ...199910466805
pathogenicity of cell culture-derived and bursa-derived infectious bursal disease viruses in specific-pathogen-free chickens.that passage of infectious bursal disease virus (ibdv) 30 and 40 times in an established cell line (bgm-70) resulted in loss of pathogenicity has been reported; however, both viruses maintained antigenicity and immunogenicity. that the passaged virus might have lost some ability to replicate in the natural host, resulting in lack of antigenic stimulation and a poor immune response, was speculated. in this study, the pathogenicity and the replication of the serorype 1 variant in strain were inves ...200111785889
ability of lactococcus lactis to export viral capsid antigens: a crucial step for development of live vaccines.the food grade bacterium lactococcus lactis is a potential vehicle for protein delivery in the gastrointestinal tract. as a model, we constructed lactococcal strains producing antigens of infectious bursal disease virus (ibdv). ibdv infects chickens and causes depletion of b-lymphoid cells in the bursa of fabricius and subsequent immunosuppression, morbidity, or acute mortality. the two major ibdv antigens, i.e., vp2 and vp3, that form the viral capsid were expressed and targeted to the cytoplas ...200314660377
avian adenovirus celo recombinants expressing vp2 of infectious bursal disease virus induce protection against bursal disease in chickens.to develop a celo virus vector that can induce protection against infectious bursal disease, celo viruses expressing the host-protective antigen vp2 of infectious bursal disease virus (ibdv) were constructed. in the engineered recombinants, the vp2 gene (the 441-first codons of the ibda polyprotein) was placed under the control of the cmv promoter. two positions in the celo genome were chosen to insert the vp2 expression cassette. the recombinants were found apathogenic, when inoculated by diffe ...200415149796
protection against very virulent infectious bursal disease virus in chickens immunized with dna vaccines.plasmid dna vaccines pcdna-vp2 expressing only vp2 protein and pcdna-vp243 expressing vp2, vp4 and vp3 proteins of very virulent infectious bursal disease virus (vvibdv) korean sh/92 strain were constructed. the expression of viral proteins from constructed dna vaccines was confirmed by an in vitro transcription/translation system and transfection in cos-7 cells. to investigate the protective efficacy of these dna vaccines, 2-week-old chickens were injected intramuscularly and intraperitoneally ...200415201032
plasmid dna encoding antigens of infectious bursal disease viruses induce protective immune responses in chickens: factors influencing efficacy.the complete polyprotein (vp2/4/3) and vp2 genes of two infectious bursal disease viruses (ibdvs) (one attenuated strain jd1 and one virulent strain zj2000) were amplified by long and accurate polymerase chain reaction (la-pcr), cloned, sequenced and inserted into plasmids pci and pcdna3 under the control of human cytomegalovirus (hcmv) immediate early enhancer and promoter. a series of dna vaccine preparations were made using liposome as the adjuvant to examine their immunogenicity. although vp ...200314609631
restriction fragment length polymorphism analysis of the vp2 gene of australian strains of infectious bursal disease virus.twenty-four australian strains of infectious bursal disease virus (ibdv) were characterized by reverse transcription/polymerase chain reaction-restriction fragment length polymorphism and compared with previously published overseas strains. a primer pair designed to amplify a 743 base pair fragment of the vp2 gene was used and restriction fragment length polymorphism profiles were determined for each strain using three restriction enzymes, bst ni, mboi and sspi. australian strains comprised 12 m ...200212593738
protection from infectious bursal disease virus (ibdv)-induced immunosuppression by immunization with a fowlpox recombinant containing ibdv-vp2.immunosuppression resulting from infectious bursal disease virus (ibdv) infection has critical health and welfare implications for birds, yet it is incompletely understood and largely overlooked as a measure of vaccine efficacy. the ability of a fowlpoxvirus recombinant (fpibd1) containing the vp2 protein of ibdv to protect against ibdv-induced immunosuppression was investigated by measuring the convalescent chicken's ability to mount antibody responses to ibdv infection, and to inactivated ibdv ...200314676010
influence of early or late start of first feeding on growth and immune phenotype of broilers.1. the changes in body weight (bw) gain, immune phenotype and viability of commercial broilers, either given feed and water immediately after hatch or food-deprived for 24 or 48 h, were analysed in order to study the effect of early or late start of first feeding. 2. chickens fed immediately had a 6.1% higher bw at slaughter age than those food-deprived for 48 h, while those chickens food-deprived for 24 h only had a 1.4% higher weight than those deprived for 48 h. 3. those fed immediately and t ...200415222418
very virulent infectious bursal disease virus in egypt: epidemiology, isolation and immunogenicity of classic vaccine.infectious bursal disease (ibd) is still a significant threat facing the egyptian poultry industry. in this study, eight very virulent ibd viruses (vvibdv), originating from acute ibd outbreaks recorded in lower and upper egypt, were studied with respect to their ability to replicate in cell culture, antigenicity and immunogenicity of classic vaccine. six continuous cell lines and one primary cell culture were tested for replication of the vvibdvs. none of the vvibdv isolates could be adapted to ...200415222739
the value of tissue imprint hybridization for rapid detection of infectious bursal disease virus from field outbreaks.the use of a peroxidase labelled pcr generated probe followed by enhanced chemiluminescence hybridization assay detected infectious bursal disease virus directly from bursal imprints on a nylon membrane. tissue imprint hybridization proved to be a simple, rapid and safe means of detecting ibd virus for screening large numbers of field samples. the pcr generated probe was highly specific for ibd virus and did not hybridize with cellular nucleic acids in control imprints. tissue imprint hybridizat ...200212379057
sequence analysis of the variable vp2 gene of infectious bursal disease viruses passaged in vero cells.korean field infectious bursal disease viruses (ibdvs) were isolated from ibdv suspected commercial chickens. a previous study revealed that these ibdv field isolates were virulent or very virulent ibdvs. the isolates were passaged three times in the chorioallantoic membrane of specific-pathogen-free embryonated chicken eggs and four times in vero cells. after passage, viral rnas were isolated and purified to determine the genetic changes. the hypervariable regions of the vp2 gene were amplified ...200415266110
comparison of in ovo and post-hatch vaccination with particular reference to infectious bursal disease. a review.in ovo vaccination is an alternative approach to post-hatch vaccination of chickens, particularly in broilers. vaccination at embryonation day 18 helps to 'close the window' of susceptibility i.e. the time between vaccination and early exposure to infectious agents compared with post-hatch vaccination. attempts on embryonal vaccination as a mode of vaccine delivery were approached from the observation that chickens already develop certain immunologic functions before hatching. the immune system ...200415230052
susceptibility of vaccinated and unvaccinated egyptian chickens to very virulent infectious bursal disease virus.the responses of vaccinated and unvaccinated chickens of different breeds to infection with very virulent infectious bursal disease virus (vvibdv) were investigated. five-week-old chickens of five egyptian breeds (fayoumi, balady, golden, mandarah, and gimmizah), and foreign white leghorn pullets were tested. in unvaccinated birds, mortality, relative bursa and spleen weight, bursal lesion score, antibody titres and the response of blood lymphocytes to mitogens were examined. the gimmizah and fa ...200212396359
quantitative measures of disease in broiler breeder chicks of different major histocompatibility complex genotypes after challenge with infectious bursal disease virus.criteria for evaluating genetic differences in resistance and susceptibility to infectious bursal disease (ibd) within a commercial broiler breeder line of chickens were compared. line a broiler breeder chickens were challenged with graded doses of animal and plant health inspection service (aphis) strain ibd virus (ibdv) and evaluated at 2 time points, 3 days postinoculation (pi) and 10 days pi. measures obtained at both time points included bursa to body weight, bursa histology, bursa lymphocy ...200212243521
a recombinant newcastle disease virus (ndv) expressing vp2 protein of infectious bursal disease virus (ibdv) protects against ndv and ibdv.infectious bursal disease virus (ibdv) causes a highly immunosuppressive disease in chickens. currently available, live ibdv vaccines can lead to generation of variant viruses. we have developed an alternative vaccine that will not create variant ibdv. by using the reverse genetics approach, we devised a recombinant newcastle disease virus (ndv) vector from a commonly used vaccine strain lasota to express the host-protective immunogen vp2 of a variant ibdv strain gls-5. the gene encoding the vp2 ...200415331738
structure-dependent efficacy of infectious bursal disease virus (ibdv) recombinant vaccines.the immunogenicity and protective capability of several baculovirus-expressed infectious bursal disease virus (ibdv)-derived assemblies as vp2 capsids, vpx tubules and polyprotein (pp)-derived mixed structures, were tested. four-week-old chickens were immunised subcutaneously with one dose of each particulate antigen. vp2 icosahedral capsids induced the highest neutralising response, followed by pp-derived structures and then vpx tubules. all vaccinated animals were protected when challenged wit ...200312706682
use of multiple antigenic peptides related to antigenic determinants of infectious bursal disease virus (ibdv) for detection of anti-ibdv-specific antibody in elisa--quantitative comparison with native antigen for their use in serodiagnosis.multiple antigenic peptides (maps) prepared for the predicted antigenic determinants on the vp2 protein of infectious bursal disease virus (ibdv) were used as antigens in enzyme-linked immunosorbent assay (elisa)--an alternative to whole viral antigen to detect anti-ibdv antibodies in the chicken sera. two maps were synthesized, which could specifically detect the anti-ibdv antibodies in serum samples by elisa. the optimum quantity of map1 and map2 required to coat the wells of the elisa plate w ...200415541277
functional restoration of the bursa of fabricius following in ovo infectious bursal disease vaccination.the primary role of the avian bursa of fabricius is to provide an essential microenvironment for b-lymphocytes to diversify their immunoglobulin genes by gene hyperconversion. infectious bursal disease (ibd) vaccination using intermediate plus vaccine strains can temporarily deplete the bursal follicles and interrupt the normal b-cell development, which is generally followed by b-cell repopulation and histological regeneration. to find evidence that functional restoration of the bursa of fabrici ...200111389958
generation of serotype 1/serotype 2 reassortant viruses of the infectious bursal disease virus and their investigation in vitro and in vivo.infectious bursal disease virus (ibdv) is the causative agent of acute or immunosuppressive disease in chickens. serotype 1 strains are pathogenic whereas serotype 2 strains neither cause disease nor protect against infection with the serotype 1 strains. the target organ of serotype 1 strains is the bursa fabricii (bf). the molecular determinants of this tropism, and therefore pathogenicity, are poorly understood. ibdv is a non-enveloped icosahedral virus particle of 60 nm in diameter, which con ...200415325078
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