Novel Antigenic Variant Infectious Bursal Disease Virus Outbreaks in Japan from 2014 to 2023 and Characterization of an Isolate from Chicken

Novel antigenic variant strains of the infectious bursal disease virus (IBDV) classified into genogroup A2d have been found in the western part of Japan since 2017. Novel antigenic variant IBDVs now occur in higher frequencies in poultry houses and have been detected in the eastern part of Japan, in...

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Main Authors: Mari Takahashi, Shiori Oguro, Atsushi Kato, Soma Ito, Nobuyuki Tsutsumi
Format: Article
Language:English
Published: MDPI AG 2024-12-01
Series:Pathogens
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Online Access:https://www.mdpi.com/2076-0817/13/12/1141
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author Mari Takahashi
Shiori Oguro
Atsushi Kato
Soma Ito
Nobuyuki Tsutsumi
author_facet Mari Takahashi
Shiori Oguro
Atsushi Kato
Soma Ito
Nobuyuki Tsutsumi
author_sort Mari Takahashi
collection DOAJ
description Novel antigenic variant strains of the infectious bursal disease virus (IBDV) classified into genogroup A2d have been found in the western part of Japan since 2017. Novel antigenic variant IBDVs now occur in higher frequencies in poultry houses and have been detected in the eastern part of Japan, indicating the spread of IBDVs despite the usual IBDV vaccination. We isolated a novel antigenic variant IBDV, designated as the B2977CE2C3 strain. The B2977CE2C3 strain had two genogroup A2d specific amino acids—lysine and isoleucine, at 221 and 252 aa—along with the other genogroup A2 common amino acids in the projection domains of the VP2 protein corresponding to the virus-neutralizing epitopes and viral pathogenicity. Experimental infection of the B2977CE2C3 strain did not produce any apparent clinical signs in the specific-pathogen-free chickens during the observation period (21 days), but atrophy of the bursa of Fabricius (BF) was apparent. The mean BF to the body weight ratio was 0.35 in negative control chickens at 21 days post-infection (pi) but 0.06 in the B2977CE2C3 infected group. An extremely high copy number of the IBDV genome (>10<sup>8</sup> copies/µL) was observed in the BF at 3 days pi, while a high copy number of the IBDV genome (>10<sup>6</sup> copies/µL) was observed in the thymus, spleen cecal tonsil, and bone marrow even though macroscopic lesions were not apparent in these organs.
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spelling doaj-art-42219bf3469d41e7b65f05775615c99d2024-12-27T14:45:31ZengMDPI AGPathogens2076-08172024-12-011312114110.3390/pathogens13121141Novel Antigenic Variant Infectious Bursal Disease Virus Outbreaks in Japan from 2014 to 2023 and Characterization of an Isolate from ChickenMari Takahashi0Shiori Oguro1Atsushi Kato2Soma Ito3Nobuyuki Tsutsumi4Nisseiken Co., Ltd., 9-2221-1 Shin-machi, Ome 198-0024, Tokyo, JapanNippon Institute for Biological Science, 9-2221-1 Shin-machi, Ome 198-0024, Tokyo, JapanNippon Institute for Biological Science, 9-2221-1 Shin-machi, Ome 198-0024, Tokyo, JapanNippon Institute for Biological Science, 9-2221-1 Shin-machi, Ome 198-0024, Tokyo, JapanNisseiken Co., Ltd., 9-2221-1 Shin-machi, Ome 198-0024, Tokyo, JapanNovel antigenic variant strains of the infectious bursal disease virus (IBDV) classified into genogroup A2d have been found in the western part of Japan since 2017. Novel antigenic variant IBDVs now occur in higher frequencies in poultry houses and have been detected in the eastern part of Japan, indicating the spread of IBDVs despite the usual IBDV vaccination. We isolated a novel antigenic variant IBDV, designated as the B2977CE2C3 strain. The B2977CE2C3 strain had two genogroup A2d specific amino acids—lysine and isoleucine, at 221 and 252 aa—along with the other genogroup A2 common amino acids in the projection domains of the VP2 protein corresponding to the virus-neutralizing epitopes and viral pathogenicity. Experimental infection of the B2977CE2C3 strain did not produce any apparent clinical signs in the specific-pathogen-free chickens during the observation period (21 days), but atrophy of the bursa of Fabricius (BF) was apparent. The mean BF to the body weight ratio was 0.35 in negative control chickens at 21 days post-infection (pi) but 0.06 in the B2977CE2C3 infected group. An extremely high copy number of the IBDV genome (>10<sup>8</sup> copies/µL) was observed in the BF at 3 days pi, while a high copy number of the IBDV genome (>10<sup>6</sup> copies/µL) was observed in the thymus, spleen cecal tonsil, and bone marrow even though macroscopic lesions were not apparent in these organs.https://www.mdpi.com/2076-0817/13/12/1141genogroupinfectious bursal disease virusisolationnovel antigenic variantpathogenicityphylogenetic tree analysis
spellingShingle Mari Takahashi
Shiori Oguro
Atsushi Kato
Soma Ito
Nobuyuki Tsutsumi
Novel Antigenic Variant Infectious Bursal Disease Virus Outbreaks in Japan from 2014 to 2023 and Characterization of an Isolate from Chicken
Pathogens
genogroup
infectious bursal disease virus
isolation
novel antigenic variant
pathogenicity
phylogenetic tree analysis
title Novel Antigenic Variant Infectious Bursal Disease Virus Outbreaks in Japan from 2014 to 2023 and Characterization of an Isolate from Chicken
title_full Novel Antigenic Variant Infectious Bursal Disease Virus Outbreaks in Japan from 2014 to 2023 and Characterization of an Isolate from Chicken
title_fullStr Novel Antigenic Variant Infectious Bursal Disease Virus Outbreaks in Japan from 2014 to 2023 and Characterization of an Isolate from Chicken
title_full_unstemmed Novel Antigenic Variant Infectious Bursal Disease Virus Outbreaks in Japan from 2014 to 2023 and Characterization of an Isolate from Chicken
title_short Novel Antigenic Variant Infectious Bursal Disease Virus Outbreaks in Japan from 2014 to 2023 and Characterization of an Isolate from Chicken
title_sort novel antigenic variant infectious bursal disease virus outbreaks in japan from 2014 to 2023 and characterization of an isolate from chicken
topic genogroup
infectious bursal disease virus
isolation
novel antigenic variant
pathogenicity
phylogenetic tree analysis
url https://www.mdpi.com/2076-0817/13/12/1141
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