Delmarva (DMV/1639) Infectious Bronchitis Virus (IBV) Variants Isolated in Eastern Canada Show Evidence of Recombination.

Mohamed S H Hassan,Carla S Coffin,Davor Ojkic,Frank Van Der Meer,Susan C Cork,Mohamed Faizal Abdul-Careem

doi:10.3390/v11111054

Mohamed S H Hassan, Carla S Coffin + Show 4 more

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https://doi.org/10.3390/v11111054

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Journal: Viruses	Publication Date: Nov 13, 2019
Citations: 75	License type: CC BY 4.0

Affiliation: University of Calgary, University of Guelph

Abstract

Infectious bronchitis virus (IBV) infection in chickens can lead to an economically important disease, namely, infectious bronchitis (IB). New IBV variants are continuously emerging, which complicates vaccination-based IB control. In this study, five IBVs were isolated from clinical samples submitted to a diagnostic laboratory in Ontario, Canada, and subjected to detailed molecular characterization. Analysis of the spike (S)1 gene showed that these five IBVs were highly related to the Delmarva (DMV/1639) strain (~97.0% nucleotide sequence similarity) that was firstly isolated from an IB outbreak in the Delmarva peninsula, United States of America (USA), in 2011. However, the complete genomic sequence analysis showed a 93.5–93.7% similarity with the Connecticut (Conn) vaccine strain, suggesting that Conn-like viruses contributed to the evolution of the five Canadian IBV/DMV isolates. A SimPlot analysis of the complete genomic sequence showed evidence of recombination for at least three different IBV strains, including a Conn vaccine-like strain, a 4/91 vaccine-like strain, and one strain that is yet-unidentified. The unidentified strain may have contributed the genomic regions of the S, 3, and membrane (M) genes of the five Canadian IBV/DMV isolates. The study outcomes add to the existing knowledge about involvement of recombination in IBV evolution.

Highlights

Infectious bronchitis (IB), an acute and highly contagious disease, is characterized by respiratory, renal, or reproductive diseases in chickens of all ages [1]
Our findings indicated that the S1 genes of our five Infectious bronchitis virus (IBV) isolates are similar to the DMV/1639 strain which was originally isolated from an infectious bronchitis (IB) outbreak in the Delmarva peninsula in the United States of America (USA) [32]
Further analysis included the elucidation of the complete genome sequences of our five IBV isolates, which demonstrated genetic evidence of recombination with the Conn vaccine, 4/91 vaccine and an unknown IBV strain

Summary

Introduction

Infectious bronchitis (IB), an acute and highly contagious disease, is characterized by respiratory, renal, or reproductive diseases in chickens of all ages [1]. The infectious bronchitis virus (IBV) is the causative agent and is an enveloped, positive-sense single-stranded ribonucleic acid (RNA) virus which belongs to the genus Gammacoronavirus of the family Coronaviridae [2]. The size of the IBV genome is approximately 27.6 kilo-bases (kb) and the genome encodes at least 10 open reading frames (ORFs), flanked by two untranslated regions (UTR), and is organized as follows: 50. Ribosomal frameshifting from the 1a reading frame into the 1ab ORF at the 50 region generates two polyproteins The process generates 15 non-structural proteins (nsps), nsps 2-16, that are necessary for replication and pathogenicity [3,4].

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