Molecular Biology, Immunosuppression and Pathogenesis of Infectious Bursal Disease Virus (original) (raw)
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The circulation of unique reassortment strains of infectious bursal disease virus in Pakistan
Journal of Integrative Agriculture, 2020
Infectious bursal disease (IBD), caused by IBD virus (IBDV), is one of the most devastating and immunosuppressive diseases of the poultry and has been a constraint on the sustainable poultry production around the globe including Pakistan. While the disease is threatening the poultry industry, the nature of predominant strains of IBDV in Pakistan remained ill-defined. In this study, an epidemiology survey was conducted in the main chicken-farming regions of Pakistan. The batch of Pakistan IBDVs genes simultaneously covering both VP1 and VP2 were amplified, sequenced, and analyzed. The unique segmentreassortant IBDVs (vv-A/Uniq-B), carrying segment A from vvIBDV and segment B from one unique ancestor, were identified as one important type of circulating strains in Pakistan. The data also discovered the characteristic molecular features of Pakistan IBDVs, which will contribute to scientific vaccine selection and effective prevention of the disease.
Frontiers in Veterinary Science, 2021
Vaccination is an essential component in controlling infectious bursal disease (IBD), however, there is a lack of information on the genetic characteristics of a recent infectious bursal disease virus (IBDV) that was isolated from IBD vaccinated commercial flocks in Malaysia. The present study investigated 11 IBDV isolates that were isolated from commercial poultry farms. The isolates were detected using reverse transcription-polymerase chain reaction (RT-PCR) targeting the hypervariable region (HVR) of VP2. Based on the HVR sequences, five isolates (IBS536/2017, IBS624/2017, UPM766/2018, UPM1056/2018, and UPM1432/2019) were selected for whole-genome sequencing using the MiSeq platform. The nucleotide and amino acid (aa) sequences were compared with the previously characterized IBDV strains. Deduced aa sequences of VP2HVR revealed seven isolates with 94–99% aa identity to very virulent strains (genogroup 3), two isolates with 97–100% aa identity to variant strains (genogroup 2), and...
Infectious bursal disease viruses (IBDVs) have a profound impact on poultry production worldwide, directly causing mortality rates of up to 100%, and indirectly through their immunosuppressive effects. Since the emergence of the antigenically modified very virulent IBDV (vvIBDV) in Egypt in late 1999, the country has experienced recurrent outbreaks with high mortality rates and typical vvIBDV gross lesions. However, a notable shift occurred in 2023, characterized by a substantial increase in reported subclinical IBDV cases exhibiting atrophied bursa and associated immunosuppression. To assess the field situation, we examined samples from 21 farms in 2023 and 18 farms from 2021 and 2022, all of which experienced IBD outbreaks based on clinical diagnosis. These samples were submitted to our laboratory for confirmatory testing and subsequently subjected to VP2-HVR sequencing. Phylogenetic analysis revealed that all samples collected in 2021 and 2022 clustered with classical virulent st...
Indian Journal of Animal Research, 2021
Background: In recent years, Infectious bursal disease is continuously occurring even after vaccination in India and requires an inclusive diagnosis. Therefore, the present study was undertaken to diagnose IBD through molecular and culture methods. Methods: One pooled sample, from each of 54 flocks having birds with IBD like symptoms, was collected. History of bird type, age and vaccination was recorded. Samples were subjected to RT-PCR, egg embryo culture and chicken fibroblast cells culture. Result: A total of 49669 out of 517900 (9.59 %) of birds, aging 3-6 weeks, were displaying the signs similar to IBD.In RT-PCR, 21 (38.88%) samples were found positive which belonged to11 (52.38%) vaccinated and 10 (47.62%) unvaccinated flocks.The RT-PCR positive samples were successfully cultivated for the virus through egg embryo and cell culture. The CEF culture was found least sensitive compared to egg embryo culture and RT-PCR.
International Journal for Agro Veterinary and Medical Sciences, 2010
The study was conducted to determine the prevalence of infectious bursal disease virus (IBDV) at different ages in commercial boilers. From Oct 2003 to Nov 2004, bursa samples collected from both vaccinated as well non-vaccinated commercially reared broiler chickens suspected of having infectious bursal disease were analyzed for the presence of IBDV using reverse transcriptase polymerase chain reaction (RT-PCR). A 743-bp fragment of the VP2 hypervaraible region from the nucleotides 701 to 1444 was amplified. Out of the 237 tested samples 103 (43.45%) were found to contain IBDV genome using RT-PCR. The percentage of positive results in all age groups despite of the discrimination between vaccinated and nonvaccinated birds was 26.53 % in 0-3 weeks, 56.30 % in 3-6 weeks and 33.34 % in 6-8 weeks of age, respectively. Results indicated increased incidence of IBDV in non-vaccinated (47.91 %) birds as compared to vaccinated birds (35.05 %).
Acta Veterinaria Hungarica, 2014
Infectious bursal disease virus is an important poultry pathogen. It is distributed worldwide and causes significant economic losses. In this study, a system was adopted for the simultaneous monitoring of vaccine and virulent strains using reverse transcription polymerase chain reaction (RT-PCR). After the decay of maternal antibodies, chickens were vaccinated at the age of 37 days with a virus of intermediate virulence and challenged at 5, 10 and 14 days post vaccination (dpv). The challenge was done with IBDV strain CH/99. Sequencing of the hypervariable region of VP2 has shown that CH/99 belongs to the very virulent group of viruses. The vaccine virus could be found in the bursa of Fabricius, spleen, thymus and bone marrow until 24 dpv. The CH/99 challenge virus was found in the bursa and lymphoid organs when chickens were challenged at 5 and 10 dpv. When challenge was performed at 14 dpv, the pathogenic virus could not be found in the bursa and other lymphoid organs.
Veterinary World, 2011
A reverse transcriptase polymerase chain reaction restriction fragment length polymorphism (RT-PCR/RFLP) technique was used for the identification and characterization of Pakistani field isolates of infectious bursal disease virus (IBDV). A total of 8 bursa samples were collected from two outbreaks during September and October 2003 from Tehsil Sumandri, Dist. Faisalabad with 40-50% mortality in commercially reared broiler chicken flocks experiencing signs typical of infectious bursal disease (IBD). Four samples were found to contain IBDV genome by One Step RT-PCR using VP2 gene specific primers. The assay amplified a 743 bp fragment from 701-1444 nucleotides. RT-PCR product was further subjected to restriction digestion using MboI and MvaI restriction enzymes. A third enzyme SspI was used to identify the very virulent phenotype. The RFLP profile was found similar for all four isolates with MvaI enzyme but different for one isolate when digested with MboI. All three MvaI-positive viruses were further found positive for SspI digestion and yielded RFLP profile similar to vvIBDV in Europe whereas one isolate was SspI negative and had a RFLP profile similar to classic IBDV strains. The clinical history of high mortality and SspI restriction enzyme positivity revealed that vvIBDV strains exist in Pakistan.
DNA Sequence, 2006
The present study was undertaken to characterize recent field isolates of infectious bursal disease virus (IBDV) by reverse transcription-polymerase chain reaction (RT-PCR) and partial sequencing of VP2 gene. The virus could be detected in 17 of 20 field samples from broiler chickens in Haryana state, India as well as in all the four vaccine strains. Nucleotide sequences of four field isolates and one vaccine strain were compared with 10 reported IBDV strains from different parts of the world. Nucleotide substitutions at 795G, 827T, 833C, 857C, 897A, 905T, 908T, 1011A and 1094G specific for very virulent (vv) strains, were maintained in all the four field isolates. However, unique nucleotide substitutions at 806A-G, 851C-T, 1010 T-C, 1019T-C and 1082T-C showed further divergence of these isolates from already reported vvIBDVs. Deduced amino acid substitutions at 222P-A, 256V-I, 279N-D, 294L-I and 299N-S specific for vvIBDV strains were also present in all the four isolates. The vaccine strain showed amino acid change 279D-N, a characteristic of attenuated vaccine strains. Phylogenetic analysis showed that all the field isolates in the present study were closely related to reported UK (UK661) and Japan (OKYM) field isolates. All the four field IBDV strains of the present study were closely related to each other but distinct from already reported vvIBDVs of India. On the basis of nucleotide sequencing and phylogenetic analysis, it is very likely that IBD causing strains in this part of India are of very virulent character and are still undergoing changes at genetic level.
The present study was carried out to inves gate and characterize the nature of infec ous bursal disease virus (IBDV) involved in the recurrent outbreaks in an experimental layer farm in Bareilly, U ar Pradesh, India using direct ssue reverse transcrip on-polymerase chain reac on (RT-PCR) followed by nucleo de sequencing of VP2 gene. A total of three acute IBD outbreaks with the interval of 4-6 months were recorded in the batch of 3-5 weeks-old layer chicks in the year 2012-2013. Tissues collected from necropsied birds were found RT-PCR posi ve for IBDV VP2 gene. Gene c analysis of the sequenced VP2 gene revealed the IBDV belonged to very virulent (vv) subtype and had amino acids at posi ons 222A, 256I, 294I, and 299S typical for vvIBDV strains isolated worldwide. It had only one unique amino acid change in the an genic peak A (210-225 aa) at posi on 212D->N (Asp->Asn), which is not observed in any of the vvIBDVs isolated in India and abroad. Phylogene c analysis revealed the isolates were more closely related to vvIBDV strains rA and rB (U.S.A.), Gx and HLJ-7 (China), OKYM (Japan), and shared >95% nucleo de homology with them. The VP2 gene shared 96.7% amino acid homology with IBDI+ vaccine strain used in India, compara vely higher among other vaccines strains, sugges ng that IBD intermediate plus (IBDI+) vaccine might provide op mum cross protec on, also for other vvIBDV strains. The vvIBDV strains remain a threat to poultry industry worldwide, and require regular monitoring and gene c analysis in order to keep track of the appearance and evolu on of an genically different IBDV strains or sub-
Infectious Bursal Disease Virus (IBDV)
Recent Advances in Animal Virology, 2019
Infectious bursal disease virus (IBDV) is one of the most important viral pathogens of chickens. This virus causes great economic losses to the poultry industry due to factors like high mortality rates and poor growth performance of the affected chickens. Despite the intensive application of different vaccines against IBDV, several outbreaks are still emerging in many parts across the globe. This chapter highlights some important basic and clinical information related to IBDV. Further, the pathological changes and the molecular pathogenesis of IBDV infection in chicken have been discussed. In addition, recent advances on the vaccine preparation and prophylaxis against the IBDV infection have been touched. There is a need for further research to find the most appropriate vaccine and control measures against the IBDV infection in chickens.