Phylogenetic and genotypic study of Infectious bronchitis virus isolated from broiler herds by RT-PCR and S1 gene sequence analysis

Evolution and formation of IBV’s new serotypes Bare continuously in processing that every year cause a lot of economic loses in poultry industries, so rapid and accurate determination test is critical in order to choose and develop suitable vaccines for controlling of this disease in every region as an important and determinative principle. Despite vaccination against IBD, this 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 happens. Specimens of trachea and lungs were taken from 40 suspected flock with respiratory problems collected from chicken farms in Fars and Chaharmahal and Bakhtiari Provinces. Samples were tested by Chicken Red Blood Cell Hem-agglutination and negative samples selected for determining Infectious bronchitis viruses by RT-PCR test. Then PCR product was purred by "High pure PCR product purification Kit" Germany (Roche) company has been sent to sequencing a piece with 464 nucleotide base pair. Sequences checked and corrected by MEGA 7 program. Phylogenetic analysis was made by MEGA 7 program using sequencing and National Center for Biotechnology Information. This study results show the majority of flocks infected by variant 2 (75% samples), then mass type (16.6% samples) and finally (8% samples) were H120 vaccine- like isolates. So in according to difference in dominant serotypes in this study with market place vaccines could not create cross immune therefore need to develop new vaccines.