Isolation And Identification Of Seven Infectiousbronchitis Virus In Henan And It Is Biological Characterisrics

Infectious bronchitis is currently one of the highly contagious respiratory diseases in chickens caused by infectious bronchitis virus (IBV) which is a member of coronavirus. IBV mainly causes damages in respiratory tissue,reproductive system and kidney, and results in decreased both egg Production and quality and poor performance. IBV is known to have high potential of point mutation, gene recombination, gene deficiency and gene insert which induce the virus variation. There are a number of IBV serorypes and there is poorer cross- Protection between them, so different serotypes and genotypes emerge frequently and could result in immunization failure. Recently, IB has occurred frequently in lots of Poultry flocks in Henan in spite of vaccination which is economically devasting to the Poultry industry. Therefore,study and Know the Phylogeny and variation on the isolates of IBV from the commercial Chickens in Henan is the key for effective control of the disease.Samples were collected from the chicken flocks with typical clinical symptoms of IB from Hebi,Puyang,Shangqiu,Xinzheng,Luoyang,Luohe,Zumadian. Virus is isolations were carried outing in 9-11 day embryonated eggs by inoculating via the allantoic cavity. The samples of embryos were detected routinely for bacteria, Newcastle disease virus(NDV)and Avian influenza virus(AIV) by culture and hemagglutination (HA)test. The negative samples were further investigated by dwarfing chicken Embryo test, Egg:embryo weight ratio as an indicator of dwarfism induced by infectious bronchitis virus Avian Pathology, growth interference with NDV And nucleic acid detection cross by RT-PCR. The data indicated that 7 isolates didn't hemagglutinate chicken red Blood cells directly but interfere with NDV. Gross lesions were observed in Chicken embryo after four Passages in chicken embryo. IBV s1 gene hypervariable region I of all isolates were successfully amplified by RT-PCR. compared to that of other IBV reference strains show that amino acid sequences higher homology were Jilin isolated strain (CK/CH/LJL/07V) and Beijing isolated strain (A2) amino acid sequences homology beween 95.4% and 99.3 %; compared with vaccines strain H120, H52, Ma5, M41, Beaudette strain, and Conn/B13dpvcontact were between the 74.2% ~ 78.8%; compared with Australian T strain and HN99 were 69.3% ~ 72.9%. all above show that infectious bronchitis virus variability quickly in Henan Province.In order to understand the epidemic of chicken IBV strains genetic variation in Henan Province, S1 gene hypervariable region of the senven IBV strains isolated in Henan between 2007 and 2008 were cloned ,sequenced and compared to that of other IBV reference strains . A phylogenetic tree based on amino acid sequences of HVR of the viruses showed that they were grouped into same cluster I , we know the nucleotide sequence homology beween 97.0% (HN-LY with the HN-ZMD) and 99.8% (HN-LH and the HN-PY), deduced amino acid sequences homology beween 93.5% (HN-ZMD and HN-LY) and 100% (HN-PY and HN-HB) based on amino acid sequences of HVR of the viruses . shared much higher homology between the viruses which were isolated in the same period, but with no distinct difference in geological origins.The results of the study demonstrated that IBV infections have been popular in the commercial chicken flocks. The recently prevalent IBVs isolated in Henan have a high variability and have strong pathogenicity to chickens. These data will be helpful to the applications of the vaccines in the field and the development of new vaccine in future.