The contribution of feathers in the spread of chicken anemia virus.

A phage-displayed single chain variable fragment (scFv) antibody library was constructed from the immune spleen cells of chickens immunized with very virulent infectious bursal disease virus (vvIBDV) strain CS89. A library consisting of around 9.2 × 107 clones was subjected to 3 rounds of panning against captured CS89 virus. Analysis of individual clones by nucleotide sequencing revealed at least 22 unique scFv antibodies binding to vvIBDV in ELISA. Testing of the scFv antibody panel in ELISA against classical, variant or vaccine strains and a wide variety of vvIBDV isolates from the UK, China, France, Belgium, Africa, Brazil, Indonesia and the Netherlands identified one antibody, termed chicken recombinant antibody 88 (CRAb 88) that was specific for vvIBDV. CRAb 88 was capable of recognizing all vvIBDV strains tested regardless of their country of origin and showed no reactivity with classical, variant or vaccine strains, lending support to the use of this scFv as a powerful diagnostic tool for the differentiation of vvIBDV strains. Immunoprecipitation studies revealed that CRAb 88 was directed towards a highly conformational epitope located within the major neutralizing protein VP2. Sequence analysis of the hypervariable region of VP2 of the IBDV strains tested indicate that Ile(256) and Ile(294) may play roles in binding of CRAb 88. This is the first reagent of its type capable of positively distinguishing vvIBDV from other IBDV strains.

Chicken recombinant antibodies specific for very virulent 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 molecular groups that were unique and distinct from overseas IBDV strains. A specific SspI site that is used to predict a very virulent IBDV phenotype was absent from all Australian strains, contrary to a previous finding by Jackwood and Sommer (1999). One Australian strain (N1/99) contained an SspI site; however, this was located at a different position than that found in very virulent IBDV strains. The results demonstrate that restriction fragment length polymorphism can be used to rapidly differentiate Australian IBDV strains from overseas strains. However, the existence of a large number of molecular groups might preclude its effectiveness for inter-strain differentiation.

https://www.tandfonline.com/doi/pdf/10.1080/0307945021000024625

Restriction fragment length polymorphism analysis of the VP2 gene of Australian strains of infectious bursal disease virus.

SUMMARY. This study aimed to genotype infectious bursal disease virus (IBDV) isolates from the Minas Gerais state poultry industry. RNA was extracted from bursae obtained from field cases without passage or commercial vaccines. Genetic subtyping of IBDV isolates and vaccine strains was carried out by the reverse transcriptase-polymerase chain reaction (RT-PCR) and restriction fragment length polymorphism (RFLP) analysis. A 588-bp fragment in the VP1 gene, an 847-bp fragment in the VP2 gene, and a 320-bp fragment in the VP3 gene were amplified by PCR and digested with restriction enzymes PstI and ScaI (VP1); BamHI, BstEII, and PstI (VP2); and NcoI, ScaI, and XbaI (VP3). Our work shows that complementing the clinical history of the outbreaks with RT-PCR followed by RFLP analysis using PstI for VP1, BamHI for VP2, and XbaI for VP3 allowed an accurate classification of a causative agent as a very virulent IBDV.

https://bioone.org/journals/Avian-Diseases/volume-49/issue-4/7351-030205R.1/Genotyping-of-Infectious-Bursal-Disease-Virus-Strains-by-Restriction-Fragment/10.1637/7351-030205R.1.pdf

Genotyping of infectious bursal disease virus strains by restriction fragment length polymorphism analysis of the VP1, VP2, and VP3 genes

Infectious bursal disease (IBD) viruses detected in commercial flocks of different regions of Argentina were analyzed by reverse transcription-polymerase chain reaction-restriction fragment length polymorphism (RFLP) of a VP2 gene fragment, followed by sequence analysis. Two out of eight IBD viruses presented an SspI restriction site, typical of the very virulent phenotype. Three IBD viruses presented a SacI restriction site, typical of classic virulent strains, and one isolate presented restriction sites for both enzymes. The Argentine IBD viruses showed three different molecular patterns by RFLP with the restriction endonuclease BstNI and five different patterns with MboI. By comparison of nucleotide and deduced amino acid sequences of the hypervariable region of the VP2 protein, four Argentine viruses were found to be closely related to Brazilian subclinical strains and two isolates were found to be related to vaccine IBDV strains in use in Argentina. Strain LD9569 was genetically characterized as a very virulent strain and was found to be closely related to international and regional vvIBDV strains. This is the first report on variability of IBDV strains circulating in Argentina.

Characterization of infectious bursal disease viruses from Argentina.

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 existence of two molecular groups within the field isolates; four samples showed one pattern of RFLPs, and the majority, 30 out of the 37 tested, showed a second RFLP pattern. Three samples tested negative for IBDV. Eight bursa samples, representing the two molecular groups, were also tested by the RT/PCR/RFLP assay as developed by Jackwood. A comparison of the RFLP profiles by the two methods indicated that four isolates belonged to molecular group 6 and 30 isolates belonged to a new molecular group. All field isolates had a very virulent phenotype. One vaccine strain, produced from a local isolate, was classified as molecular group 6. The other two vaccine strains had RFLPs that differed from those of the field isolates.

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.

Weisman Y

Papers

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.