Phylogenic study and strain characterization of Infectious bronchitis virus isolated from broiler herds by RT-PCR and S1 gene sequence analysis

Evolution and creation of IBV’s new serotypes continuously in processing that every year cause a lot of economic loses in poultry industries, so rapid and accurate determination in order to choose and develope suitable vaccines for controling this disease in every region as an important and determinative principle. Infectious bronchitis disease is one of the economical important disease in the poultry industry that every year cause a lot of economic loses and despite vaccination also it happen. Specimens of trachea and lungs taken from ?? suspected flock with respiratory problems collected from chicken farms in Fars and Chaharmahal and Bakhtiari Provinces. Samples tested by Chicken Red Blood cell Hem-agglutination and negative samples selected for determining Infectious bronchitis viruses by RT-PCR test. Then PCR product purred by "High pure PCR product purification Kit" Germany (Roche) company has been sent to sequencing a piece with ??? nucleotide base pair. Sequences checked and corrected by MEGA ? program. Phylogenetic analysis made by MEGA ? program using sequencing and National Center for Biotechnology Information. This study results show the majority of flocks infected by variant ? (??% samples), then mass type (??.?% samples) and finally (?% samples) were H??? vaccine- like isolates. So in according to difference in dominant stereotypes in this study with market place vaccines could not create cross immune therefore need to develop new vaccines.