Identification Of Isolated Strains Of Avian Infection Bronchitis Virus And Analysis 3CL Gene Fragment

Infectious bronchitis (IB) has occurred frequently in poultry flocks all over the world and has caused severe economic losses in recent years. with the vairety of clinical phenotype and numerous serotypes,it becomes more and more difficult to prevent and Avian Infectious Bronchitis infection. All ages,sexes,types of chickens are susceptible to the disease . Layers is often found with declinein egg production and egg quality. This disease manifests that all ages,sexes,types of chickens are susceptible to thedisease.Broiles is often found with high incidence and mortality, even induce to low weight gain and low efficiency of feedstuffs, while layers is often found with declinein egg production and egg quality. Because of having the vairety of the serotypes of Avian Infectious Bronchitis.it is necessary and important to analyse and study the serotypes of Avian Infectious Bronchitis in order to preventing it.In recent years,scientists have done much research about the etioloty and antigentity and serotype of the pathogenic Avian Infectious Bronchitis in China.In this research, two fujian strains isolated from peafowl (PF)and poultry (GZ) isolated were studied in the experiments of etioloty,virus-neutralization and genetic analysis of 3CL gene fragment.Now to analyse the development of its etiology ,pathogeny and serial and antigenic relation between Massachusetts, YX PT GZ,and PF is very important.This study is useful for undertanding the properties of the wildlife of Infectious Bronchitis isolates,and also provide important information for the basis of the choice of the vaccine isolates and preventive epidemic plan of Infectious Bronchitis, and aslo supplied useful information for the work of alpha taxonomy and the development trend of etiology in fujian province.In this reasearch ,five Infectious Bronchitis isolates were investigated systematically.We reasearched GZ,and PF isolate's etiology and serotype.And 3CL gene fragment of GZ isolated strain were sequenced and analyzed.1.The sample materials were taken from the kidney and windpipe of peafowl and poultry. They were inoculated into the SPF chicken embryos.Through collecting allantoic fluid of embryos,we obtained two typical PF and GZ strains that have highcontents.2.The viron were shown spherical, thecal,with baculiform spike (club shaped peplomers) ,about 110～125nm in diameter by electronmicroscopy.3. Hemagglutination test: obatined some different time of allantoic fluid (36h,48h,72h,96h and 120h)which are treated with 1% pancreatin be tested the valence of hemagglutination.The finding of the present study can be summarized as:it is obvious that after inoculated 48h and 72h unadapted to SPF chicken embryos of strains isolated have higher than others in the valence of hemagglutination. To contrast with physiological saline and PBS buffer solution,we concluded that allantoic fluid treated with PBS buffer solution have stable the valence of hemagglutination.And with the prolong time of processing,the valence of hemagglutination is gradually improved,and after processed 4 hour, the valence of hemagglutination is stable.4. According to immunity procedure, the ond- day-old SPF chickens could be infected with GZ and PF by ocular,nasal way.When chickens did'nt have obvious clinical feature,we take the thropple, bowels,kidney,lung and hepar about pathogeny in microscopy.we observed that central vein of heparg were infiltrated a number of inflammatory cell,and Partial hepatocyte were granulovacuolar degeneration and Vacuolation.Renal tubular cell appeared steatosis and vacuolation .And venal glomerulus and Proventriculus were infiltrated huge amounts of inflammatory cell. We can see edema of submucous thropple and so on.5.Using ciliary activity of chick embryo tracheal organ cultures(TOC) as a indicator system,five Infectious Bronchitis isolates: PF, GZ, YX , PT and Mass strain were checked in the cross-neutralization test. GZ strain be compared with YX,PT,PF strains ,we can find that these four strains belong to homologous serotype but different Subtype. GZ strain and Mass strain are heterologous serotype. PF strain Compared with PT,GZ strains, they were homologous serotype but different Subtype, PF strain and Mass strain,YX strain are heterologous serotype.The isolated PF and GZ had certain antigen correlation with the other Infectious Bronchitis.The result demonstrated that the isolated GZ and PF strains ,which were a member of the family Coronaviridae,genus Coronavirus.6.Phylogenetic analysis of the nucleotide sequence and the deduced amino acid sequence of 3CL gene fragment of GZ strain demonstrated: phylogenetic trees constructed by the neighbor jioning method showed that GZ was most closed related to Beadutte isolates from USA. But GZ was in far relation to BJ,LX4 and pf/CH/LKQ3/03 strains isolates from China.Compared to Beadutte ,we can conclude that relative sites of nucleotide sequence and the deduced amino acid sequence of 3CL gene fragment have similar tendency of variation.According to phylogenetic analysis of the nucleotide sequence and the deduced amino acid sequence of 3CL gene fragment ,we concluded that high homology be unconsonant with clinical phenotype. For example, compared to Beadutte , GZ strain was most closed related to Beadutte which are respiratory syndrome in the phylogenetic trees of the nucleotide sequence and the deduced amino acid sequence of 3CL gene fragment.7. This research manifests that the homology of the nucleotide sequence and the deduced amino acid sequence of 3CL gene fragment,etiology,pathogeny and serotype have not a certain relation. The area is very important in the reation between pathogeny and serotype...