Characterization of immunosuppression of genotype A2dB1 variant infectious bursal disease virus isolated in Malaysia using specific pathogen-free and commercial broiler chickens

Vet World Vol.18 April-2025 Article - 6

Research Article

Veterinary World, 18(4): 799-807

https://doi.org/10.14202/vetworld.2025.799-807

Paniz Zarghami Dastjerdi¹, Mohd Hair Bejo^1,2, Nor Yasmin Abd Rahaman², Abdullahi Abdullahi Raji^1,3, Roikhwan Soontravanich⁴, Shen Rong Tai⁵, and Abdul Rahman Omar^1,2

1. Laboratory of Vaccine and Biomolecules, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
2. Department of Veterinary Pathology and Microbiology, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
3. Department of Veterinary Pathology, Faculty of Veterinary Medicine, Usmanu Danfodiyo University, 840212 Sokoto, Nigeria.
4. Regional Operating Unit South East Asia and South Korea, Boehringer Ingelheim Singapore Private Limited, 199555 Singapore.
5. Boehringer Ingelheim Sdn. Bhd. Level 23A, Mercu Aspire, No.3, Jalan Bangsar, KL Eco City, Kuala Lumpur 59200, Malaysia.

Background and Aim: Infectious bursal disease (IBD) is an immunosuppressive disease caused by the IBD virus (IBDV), which adversely affects poultry vaccination programs. The novel variant IBDV (nvIBDV) has recently emerged in various regions, including Malaysia, raising concerns about its immunosuppressive potential and impact on Newcastle disease (ND) vaccination. This study aimed to investigate the immunosuppressive effects of the Malaysian nvIBDV strain (UPM1432/2019) in specific-pathogen-free (SPF) and broiler chickens and evaluate its influence on ND vaccine efficacy.

Materials and Methods: SPF chickens were orally infected with nvIBDV across three passage levels to study virus-induced clinical signs, lesions, and atrophy. Broiler chickens were vaccinated with live and killed ND vaccines and subsequently challenged with nvIBDV to measure ND antibody titers. The genotype of nvIBDV was characterized using sequence analysis of segments A and B. Bursal histopathology and statistical analyses were conducted to evaluate the virus’s immunosuppressive effects.

Results: Infected SPF chickens displayed no clinical signs but showed significant bursal atrophy and lesions across all passages (p < 0.05). Broilers infected with nvIBDV exhibited no mortality or clinical signs; however, ND antibody titers significantly declined by 14 days post-challenge (1493.0 ± 746.1) compared with the unchallenged group (2975.7 ± 189.5; p < 0.01). Histopathological analysis revealed severe depletion of the bursal follicles, lymphoid cell aggregation, necrosis, and hemorrhage. Genotyping of nvIBDV identified as genotype A2dB1, consistent with strains from other regions.

Conclusion: The Malaysian nvIBDV strain causes subclinical infections in SPF and broiler chickens, resulting in bursal atrophy and reduced ND vaccine-induced antibody titers. Silent spread and immunosuppressive effects present significant challenges to poultry health management and vaccination efficacy. Enhanced diagnostic and biosecurity measures are crucial for mitigating its impact.

Keywords: bursal atrophy, immunosuppression, Newcastle disease vaccination, novel variant infectious bursal disease virus, poultry health.

How to cite this article: Dastjerdi PZ, Bejo MH, Rahaman NYA, Raji AA, Soontravanich R, Tai SR, and Omar AR (2025) Characterization of immunosuppression of genotype A2dB1 variant infectious bursal disease virus isolated in Malaysia using specific pathogen-free and commercial broiler chickens, Veterinary World, 18(4): 799–807.

Received: 2024-10-29 Accepted: 2025-03-07 Published online: 2025-04-07

Corresponding author: Abdul Rahman Omar E-mail: aro@upm.edu.my

DOI: 10.14202/vetworld.2025.799-807

Copyright: Dastjerdi, et al. This article is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/ by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/ publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.