Vet World   Vol.11   October-2018  Article-25

Identification and characterization of a novel infectious bursal disease virus from outbreaks in Maharashtra Province of India

Background and Aim: The 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 Methods: The 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.

Results: The 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.

Conclusion: The 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. Keywords: adaptation, chicken embryo fibroblast, epidemiology, isolate infectious bursal disease virus, VP2.

Keywords: adaptation, chicken embryo fibroblast, epidemiology, isolate infectious bursal disease virus, VP2.

How to cite this article: Awandkar SP, Tembhurne PA, Kesharkar JA, Kurkure NV, Chaudhari SP, Bonde SW, Ingle VC (2018) Identification and characterization of a novel infectious bursal disease virus from outbreaks in Maharashtra Province of India, Veterinary World, 11(10): 1516-1525.

Received: 09-09-2018  Accepted: 29-09-2018     Published online: 29-10-2018

Corresponding author: Sudhakar P. Awandkar   E-mail: drspawandkar@gmail.com

DOI: 10.14202/vetworld.2018.1516-1525

Copyright: Awandkar, 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.