Abstract
Recently 2018, four strains of infectious bronchitis virus (IBV) were isolated from vaccinated and non-vaccinated broiler flocks from different chicken farms in different cities in Iraq. The pathogenic characters were assessed for the four IBV strains. Test chickens were infected by the four strains releasing an immune response. Noticeable results showed by cross neutralization assays which revealed that strains antigenically distinct from classic IBV strains of H120, M41, Conn, and Gray. Compared to H120 vaccine strain, short insertion, point mutation, and deletion occurred at many positions in the S1 protein of the four strains. Two of the four strains had the motif (HRRRR), which was considered identical to that of the epidemic IBV strains in Iraq. Another two strains had new motifs (HRLRR and RRYRR) emerged in the isolated strains. These Four strains were also genetically different from the vaccine strains and non-Iraqi IBV strains but closely related to large numbers of USA and China, Singapore and India strains. The isolates and 14 reference IBV strains were clustered into three distinct groups (I-III). The four strains were categorized into groups III, forming a big phylogenetic branch, which is closely related to USA IBVs and Singapore IBVs whereas the vaccine strains belonging to group I and II are genetically distant from groups III. The results from this study indicate that different IBV strains circulate in the chicken population in Iraq.
Highlights
Corona virus is the main cause of avian infectious bronchitis (IBV) [1] which is an acute and highly contagious disease of chickens
Four infectious bronchitis virus (IBV) strains (MK562374, MK562375, MK562376, MK562377) were isolated during (2018-2019) as mentioned in Table 1 with known source viruses four vaccine strains were obtained from Babylon veterinary hospital (H120, M41, Conn and gray). 10 day old healthy chicken embryo were injected with the viruses in the allantoic cavities, later after 72 hours allantoic fluid was collected and frozen at -8oC for the step (RNA extraction), from the pathogenic signs observed on chicken embryo such as curled and Dwarfed embryo IBV was confirmed as well as to the molecular detection (RT_PCR) for N protein gene [7]
This study confirmed that different genotype of IBV were circulating in the population in Iraq
Summary
Corona virus is the main cause of avian infectious bronchitis (IBV) [1] which is an acute and highly contagious disease of chickens. The main clinical sings that could appear through the infection is tracheal rales, respiratory system, including gasping, coughing, sneezing and nasal discharge. Respiratory distress with decreasing in the egg production has been reported due to the infection in laying fowls [2]. Kidney lesions were reported by some researcher [1,3] IB is one of the major problems in poultry industry in many countries which has caused significant economic loss. Serological and molecular characterization of IBVs isolates very important. Coronaviridae the family which IBV belongs to it and genome consists of a single-stranded positive sense RNA encoding four structural proteins
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
