RESUMO
Background:Infectious bronchitis is a highly contagious disease which may cause poor weight gain and low feed efficiency in infected chickens. There are a large number of reported serotypes/genotypes, which makes the control of the disease more difficult through vaccination. However, there are only a few amino acid differences in the S1 protein of vaccine and wild type strains which are responsible for protection
Objectives: The purpose of this study is to compare IBV variants isolated from commercial chicken flocks in Iran with currently used vaccine strains
Methods: The partial S1 gene of the spike protein, covering a hypervariable and constant regions, was amplified and sequenced using conventional RTPCR
Results: Phylogenetic analysis of amino acid sequences revealed that eight of total nine isolates were divergence at least 21.8% from vaccinal Massachusetts serotypes, and six of nine isolates were divergence at least 22.7% from 4/91, and none of the nine isolates were similar to Dutch-type, D274,vaccine serotypes
Conclusions: These findings are essential for continuous surveillance disease control strategies and monitoring of variants, and thus emphasize on the importance of improving the vaccination program in Iran
RESUMO
Infectious bronchitis is an acute, highly contagious, viral disease of poultry with worldwide distribution, and is continuously evolving through point mutation and recombination of their genome; subsequently the emergence of IBV variants complicates disease control. To investigate genetic characterization of new IBV variants isolated from commercial chicken flocks in Iran collected between 2009 and 2010. The partial S1 gene of the spike protein, covering a hypervariable and constant regions, was amplified and sequenced using conventional RT-PCR. Phylogenetic analysis revealed four viruses designated as Razi-HKM891, Razi-HKM892, Razi-HKM893 and Razi-HKM894. Deduced amino acid sequence comparison with other IBV genotypes, published in the GenBank database, indicated that the isolates Razi-HKM891 and Razi-HKM894 were placed into the pathogenic 793/B serotype. However, the isolates Razi-HKM892 and Razi-HKM893 were different with previously described isolates in Iran. The Razi-HKM893 is closely related to recently published isolates from countries in Middle East and likely indigenous to Iran. These findings is essential for improving the disease control strategies and thus emphasize the importance of continuous surveillance of the disease and of sharing the information to the global scientific community, which would help to fill the epidemiological gaps in the regions and to validate the robustness of diagnostic screening