Pathogenicity analysis of one isolate of avian infectious bronchitis virus from Hefei
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.
IBVisolate from Hefei of Anhui ProvinceGI-22 genotypepathogenicity
万方数据
维普
