To investigate the epidemiology of avian infectious bronchitis virus(IBV)and study the pathogenicity of IBV isolate,we isolated the IBV field strain from a clinical sample of chickens sus-pected to be infected with infectious bronchitis virus(IBV)from Hefei,Anhui Province,named HF210416.Sequencing analysis of the S1 gene showed that HF210416 belonged to the GI-22 geno-type,which was significantly differed from that of the reference GI-22-type strains,with homology ranging only from 84.5％to 87.8％.Recombinant analysis showed that HF210416 was a recombi-nant strain,with YX10(GI-19)as the major parent and YN(GI-19)as the minor parent.2-day-old SPF chicks infected with the HF210416 isolate showed clinical symptoms such as breathing with difficulty,depression and excreting watery droppings;the infected chicks had a rapid onset of dis-ease,with mortality occurring on the second day of inoculation,and mortality persisted until the fifth day,with 33.33％(5/15)mortality rate.The infected chicks recovered the 14th day after inoculation.RT-PCR detection of pharyngeal-anal swabs showed that the virus shedding by infected chicks could be continuously detected within 14 days of the test period;Enlarged and pale kidney as well as urate deposition in the kidney were observed in infected dead and undead chicks;and the HE staining of histopathological slices showed that the cilia of trachea were removed.Immunohis-tochemistry showed that obvious viral signals were observed in the trachea,lungs,and kidneys.The viral load of various tissues was detected by RT-qPCR and it showed that HF210416 had the high-est replication efficiency in kidney tissues,then in cecum tonsils and trachea.The results of serum neutralization test showed that HF210416 had a better neutralization effect on GI-22 homologous strains,but poorer neutralization effect on other genotypes strains,suggesting that HF210416 is not suitable for vaccine candidate.In conclusion,the GI-22 isolate HF210416 is highly pathogenic and nephrotropic to chicks,and its genomic genetic characteristics and immunogenicity are differ-ent from those of other strains.This study enriches the resources of IBV strains and provides refer-ence data for understanding of the prevalence and pathogenicity of GI-22 genotypes in China.
关键词
鸡传染性支气管炎病毒/安徽合肥分离株/GI-22型/致病性
Key words
IBV/isolate from Hefei of Anhui Province/GI-22 genotype/pathogenicity
维普
万方数据