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Genetic characterization of infectious bursal disease viruses associated with gumboro outbreaks in commercial broilers from asyut province, egypt.

ABSTRACT: Ten infectious bursal disease virus (IBDV) field strains were isolated from 15 broiler flocks located in various parts of Asyut, Egypt. Seven strains were subjected to comparative sequencing and phylogenetic analyses to help provide optimal control program for protection against IBDV infection. Sequence analysis of a 530?bp hypervariable region in the VP2 gene revealed that the rate of identity and homology was around 95.6~99.1%. Sequence characterization revealed the 7 strains identified as vvIBDV with the four amino acids residues typical of vvIBDV (242I, 256I, 294I, 299S). The BURSA-VAC vaccine was the nearest vaccine in sequence similarity to the local examined IBDV strains followed by CEVACIBDL then Bursine plus and Nobilis Gumboro indicating its probable success in the face of incoming outbreaks when using these vaccines. Phylogenetic analysis revealed that the presence of three clusters for the examined strains and are grouped with reference very virulent IBDVs of European and Asian origin (Japanese and Hong Kong) strains suggesting the different ancestors of our isolates. The antigenic index showed a number of changes on the major and minor hydrophilic antigenic peaks of the virus surface structures indicating a new genetic evolution of the surface structure epitopes that may lead to vaccination failure and reemergence of the disease.

SUBMITTER: Mohamed MA

PROVIDER: S-EPMC4060563 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Genetic characterization of infectious bursal disease viruses associated with gumboro outbreaks in commercial broilers from asyut province, egypt.

Mohamed Moemen A MA Elzanaty Kamal E S KE Bakhit Bakhit M BM Safwat Marwa M MM

ISRN veterinary science 20140209

Ten infectious bursal disease virus (IBDV) field strains were isolated from 15 broiler flocks located in various parts of Asyut, Egypt. Seven strains were subjected to comparative sequencing and phylogenetic analyses to help provide optimal control program for protection against IBDV infection. Sequence analysis of a 530 bp hypervariable region in the VP2 gene revealed that the rate of identity and homology was around 95.6~99.1%. Sequence characterization revealed the 7 strains identified as vvI ...[more]

PMID: 24977049

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Project description:AimThe study was undertaken to isolate infectious bursal disease virus (IBDV) from clinical cases in broiler and cockerel flocks of Maharashtra state, India, and its molecular epidemiological investigation.Materials and methodsThe morbid bursal tissues were collected from flocks suspected for IBD. The samples were subjected for virus adaptation in primary chicken embryo fibroblast (CEF) cells followed by confirmation by reverse transcription polymerase chain reaction (RT-PCR) for partial VP2 sequence and phylogenetic analysis.ResultsThe isolation of IBDV from field samples took seven blind passages for adaptation in CEF. The cytopathic effects included rounding, aggregation, vacuolation, and detachment of the cells. The RT-PCR showed amplification of 627 bp amplicon specific to the primers for VP2 gene fragment which confirmed successful adaptation and isolation of IBDV using CEF. The nucleotide and deduced amino acids based on phylogeny clustered the current isolate in a distinct clade with classical virulent and antigenic variants. It showed divergence from very virulent (vv) and vaccine strains of Indian origin. The isolate showed unique amino acid substitution at A329V as compared to all other IBDVs. The variation in key amino acids was reported at A222, I242, Q249, Q253, A256, T270, N279, T284, I286, L294, N299, and V329. It shared conserved amino acids at position A222, I242, and Q253 as reported in vvIBDV isolates. However, the amino acids reported at position T270, N279, T284, L294, and N299 are conserved in classic, antigenic variant and attenuated strains of IBDV. The amino acids at positions N279 and T284 indicated that the isolate has key amino acids for cell culture replication.ConclusionThe IBDV field isolate does not reveal the full nucleotide sequence signature of vvIBDV as well as vaccine strains. Hence, we can conclude that it might not belong to vvIBDVs of Indian origin and the vaccine strain used in the region. This may be suggestive of the evolution of the IBDV in the field due to the coexistence of circulating field strains and live attenuated hot strains, resulting into morbidity and mortality, warranting the need for safer protective vaccines, and implementation of stringent biosecurity measures to minimize loss to farmers.

Project description:Background and aimInfectious bursal disease (IBD) or Gumboro disease is one of the most detrimental diseases in the poultry industry worldwide. Previous scientific studies have shown that live IBD vaccination might induce transient immunosuppression, leading to suboptimal vaccine responses, and therefore lack of protection against other infectious diseases; therefore, selecting an IBD vaccine in commercial farms is a concern. This study aims to compare two commercially attenuated IBD vaccines (intermediate and intermediate-plus strains) in terms of safety and antibody response to IBD and Newcastle disease viruses (NDV) in commercial broilers.Materials and methodsOverall, 216 Cobb broiler chickens were divided into three groups based on the IBD vaccine strain administered: V217 strain (Group 1), M.B. strain (Group 2), and an unvaccinated group (Group 3). Groups 1 and 2 were orally vaccinated with Hitchner B1 NDV vaccine strain 7 days after IBD vaccination. Blood samples were collected at IBD vaccination day (15 days of age) and at 7, 14, 21, and 28 days post-IBD vaccination. The immunosuppressive effects of the IBD vaccination were determined by NDV antibody response, the bursa:body weight (B:BW) ratio, and the histopathological lesion scores of the bursa of Fabricius. Phylogenetic analysis was also performed.ResultsPhylogenetic analysis revealed that the M.B. strain belonged to a very virulent IBD strain, whereas the V217 strain belonged to a classical IBD virus strain. NDV antibody titers of the two vaccinated groups increased after ND vaccination, reaching their maximum at 14 days post-ND vaccination and decreasing thereafter. The V217 group presented the highest NDV humoral response from 7 days post-vaccination (dpv) to the end of the study. The mean NDV antibody titer of the V217 group was significantly (p<0.05) higher than that of the M.B. group at 14 dpv. In addition, the V217 strain-induced lower bursal lesions post-IBD vaccination and a higher B: BW ratio at 7 and 21 dpv compared to the M.B. group. The higher B: BW ratio, lower bursal lesions, and higher ND antibody response present in the V217 group indicate that the V217 strain induces lower immunosuppressive effects compared to the M.B. strain.ConclusionThe results of this study indicate that IBD vaccine selection merits consideration, as avoiding the immunosuppressive effects induced by live IBD vaccination and the consequent impact on response to other vaccines is important.

Project description:Campylobacter jejuni is considered as a chicken commensal. The gut microbiota and the immune status of the host may affect its colonization. Infectious bursal disease virus (IBDV) is an immunosuppressive virus of chickens, which allows secondary pathogens to invade or exacerbates their pathogenesis. To investigate the effect of IBDV-induced immunosuppression on the pathogenesis of C. jejuni, broiler chickens were inoculated with a very virulent (vv) strain of IBDV at 14 days post hatch followed by C. jejuni inoculation at 7 (Experiment A) or 9 (Experiment B) days post virus (IBDV) inoculation.vvIBDV-infection led to a depression in caecal lamina propria B lymphocytes and the anti-C. jejuni-antibody response starting at 14 days post C. jejuni inoculation (pbi). The C. jejuni-colonization pattern was comparable between mono-inoculated groups of both experiments, but it varied for vvIBDV?+?C. jejuni co-inoculated groups. In Experiment A significant higher numbers of colony forming units (CFU) of C. jejuni were detected in the caecum of co-inoculated birds compared to C. jejuni-mono-inoculated birds in the early phase after C. jejuni-inoculation. In Experiment B the clearance phase was affected in the co-inoculated group with significantly higher CFU at 21 days pbi compared to the mono-inoculated group (P?<?0.05). No major differences were seen in numbers local lamina propria T lymphocyte populations between C. jejuni-inoculated groups with or without vvIBDV-infection. Interestingly, both pathogens affected the microbiota composition. The consequences of these microflora changes for the host have to be elucidated further.Our data suggests that the timing between viral and bacterial infection might affect the outcome of C. jejuni colonization differently. Our results confirm previous studies that anti-Campylobacter-antibodies may specifically be important for the clearance phase of the bacteria. Therefore, as vvIBDV is widely distributed in the field, it may have a significant impact on the colonization and shedding rate of C. jejuni in commercial poultry flocks. Subsequently, successful IBDV-control strategies may indirectly also benefit the gut-health of chickens.

Project description: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 two strains with 100% identity to the vaccine strain (genogroup 1) of IBDV. The phylogenetic analysis also showed that the isolates formed clusters with the respective genogroups. The characteristic motifs 222T, 249K, 286I, and 318D are typical of the variant strain and were observed for UPM1219/2019 and UPM1432/2019. In comparison, very virulent residues such as 222A, 249Q, 286T, and 318G were found for the vvIBDV, except for the UPM1056/2018 strain with a A222T substitution. In addition, the isolate has aa substitutions such as D213N, G254D, S315T, S317R, and A321E that are not commonly found in previously reported vvIBDV strains. Unlike the other vvIBDVs characterized in this study, UPM766/2018 lacks the MLSL aa residues in VP5. The aa tripeptides 145/146/147 (TDN) of VP1 were conserved for the vvIBDV, while a different motif, NED, was observed for the Malaysian variant strain. The phylogenetic tree showed that the IBDV variant clustered with the American and Chinese variant viruses and are highly comparable to the novel Chinese variants, with 99.9% identity. Based on the sequences and phylogenetic analyses, this is the first identification of an IBDV variant being reported in Malaysia. Further research is required to determine the pathogenicity of the IBDV variant and the protective efficacy of the current IBD vaccines being used against the virus.

Project description:Recurrent outbreaks of infectious bursal disease (IBD) have become a burning problem to the poultry industry worldwide. Here, we performed genetic analysis of IBD virus (IBDV) field isolates from recent outbreaks in various poultry farms in India. The sequence analysis of IBDV VP2 hypervariable region revealed amino acid pattern similar to that of very virulent (222A, 242I, 253Q, 256I, 272I, 279D, 284A, 294I, 299S and 330S) and intermediate plus virulent (222A, 242I, 253Q, 256I, 272T, 279N, 284A, 294I, 299S and 330S) type whereas analysis of VP1 revealed presence of sequence similar to that of very virulent (61I, 145T) and unique (61I, 141I, 143D, 145S) type in field isolates. Among the eight field isolates, two isolates contained very virulent type VP2 and unique type VP1, three contained intermediate plus virulent type VP2 and unique type VP1 whereas five contained both VP2 and VP1 of very virulent type. The phylogenetic analysis based on VP2 nucleotide sequence showed clustering of all eight isolates close to known very virulent strains whereas based on VP1, five isolates formed unique cluster and three isolates were placed close to very virulent strains. The isolates forming unique VP1 cluster showed highest similarity with classical virulent IBDVs suggesting their possible evolution from segment B of non-very virulent IBDVs. Interestingly, these five isolates were responsible for outbreaks in four different farms located at three different geographic locations in India. These observations indicates genetic reassortment between segment A and segment B from co-infecting IBDV strains leading to emergence of very virulent strains and their widespread prevalence in Indian poultry farms. The presence of 272I and 279D in VP2 protein of five field isolates may explain possible cause of Gumboro intermediate plus vaccine failure in prevention of the outbreaks. However, mortality caused by other three strains which are antigenically similar to VP1 of intermediate plus vaccine strains could not be explained and the possible role of their unique VP1 in enhancing the pathogenesis needs to be investigated further.

Dataset Information

Genetic characterization of infectious bursal disease viruses associated with gumboro outbreaks in commercial broilers from asyut province, egypt.

Publications

Genetic characterization of infectious bursal disease viruses associated with gumboro outbreaks in commercial broilers from asyut province, egypt.

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