Abstract
Avian Infectious bronchitis virus (IBV), a major pathogen of commercial poultry flocks, circulates in the form of multiple ever emerging variants threatening the poultry industry. This study was conducted to survey the presence of IBV from Luxor Governorate during 2015 -2016. Examination of 43 pooled samples including trachea and kidney homogenates by real time RT- PCR for N gene, revealed 35 (81.4%) out of 43 commercial broiler flocks were positive to IBV. The 400-bp of HVR3 of the S1 gene of ten selected samples were amplified by RT-PCR, sequenced, and aligned for phylogenetic and amino-acid similarity analyses. The ten IBV viruses share from 71% to 90.8% homologies between each other but are very different from the vaccinal strains (H120, MA5, M48, 4/91 and CR88) used in Egypt with 62.6 to 84.7 % similarities. Phylogenetic analysis revealed that all the Luxor detected viruses were grouped within the Variant 2 IBV cluster together with the D1456-like Egyptian IBVs but in a different subcluster. Monitoring the emerging IBV variants is extremely important for establishing an effective control strategy for the disease in Luxor and surrounding area.
Highlights
Avian infectious bronchitis (IB) is an economically important, acute, highly contagious disease of chickens and other fowl, caused by the avian coronavirus infectious bronchitis virus (IBV)
The aim of this study is to provide information on the molecular characteristics and the phylogenetic relationship of IBV strains in Luxor in comparison to other strains reported in Egypt
A large number of IBV variants exist worldwide due to mutations, insertions/deletions, and recombination events that affect the viral genome, having an economic impact on poultry production globally (Jackwood et al, 2005; de Wit et al, 2011). These genetic changes result in antigenic variations between different IBV strains making the control of IBV an extremely challenging task
Summary
Avian infectious bronchitis (IB) is an economically important, acute, highly contagious disease of chickens and other fowl, caused by the avian coronavirus infectious bronchitis virus (IBV). IBV is an enveloped, single-stranded, positive sense RNA, belonging to the genus Gammacoronavirus, subfamily Coronavirinae, family Coronaviridae, order Nidovirales. It has a 27 to 28 kb genome encoding four structural proteins, spike (S), membrane (M), envelope (E), and nucleocapsid (N) (Perlman et al, 2008; Gelb, 2013). Since the N gene is highly conserved even among IBV isolates of different serotypes and is abundant in infected cells (Williams et al, 1992; Spencer and Hiscox, 2006), it is often the target for nucleic acid based virus identification in diagnostic laboratories
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