Pathogenicity of a QX-like avian infectious bronchitis virus isolated in China

Abstract

Avian infectious bronchitis is a serious and highly contagious disease caused by infectious bronchitis virus (IBV). We isolated a highly virulent IBV strain (CK/CH/JS/TAHY) from kidneys of diseased chickens. Phylogenetic analysis based on the S1 gene revealed that CK/CH/JS/TAHY clustered with the QX-like type. The S1 gene has 1,620 nucleotides and encoded a polypeptide of 540 amino acids with typical coronavirus cleavage recognition sites of HRRR. About 1-day-old specific pathogen-free White Leghorn chickens inoculated with CK/CH/JS/TAHY at 10 5.5 EID 50 exhibited clinical signs including coughing, sneezing, nasal discharge, and tracheal vocalization accompanied by depression with 84% mortality and 100% morbidity. The kidneys of dead birds were swollen and pale and exhibited severe urate deposition. Histopathological examination revealed kidney hemorrhages, multifocal necrosis of the renal tubules and trachea with cilia loss, sloughing of epithelial cells, and edema of the lamina propria. IBV-specific antibodies appeared at 10 D post-infection. Chickens vaccinated with a CK/CH/JS/TAHY oil-emulsion vaccine showed 26.7% morbidity and 3% mortality indicating a protective effect. In conclusion, the IBV strain is a virulent avian IBV and that exhibited severe pathogenicity in chickens and is a vaccine candidate to prevent infection by Chinese QX-like nephropathogenic IBV strains.

A highly pathogenic GI-19 lineage infectious bronchitis virus originated from multiple recombination events with broad tissue tropism

“…Coincidently, no obvious gross lesions were observed and viral antigens were not detected by IHC in the proventriculi of chickens infected with the isolate I0305/19, although the isolate I0305/19 can replicate efficiently in the proventriculi by viral titration using 9-day-old SPF chicken eggs. In addition, only very mild respiratory signs were observed in both the commercial broilers and the SPF chickens infected with isolate I0305/19; however, other reports demonstrated that the GI-19 viruses could induce obvious respiratory signs (Liu and Kong et al, 2004;Benyeda et al, 2009;Choi et al, 2009;Zhong et al, 2016;Khanh et al, 2018;Xu et al, 2018;Li et al, 2019;Ren et al, 2019a;Yan et al, 2019). The isolate I0305/19 can replicate efficiently in both the trachea and lungs in the infected SPF chickens, which was demonstrated by viral titration in SPF chicken eggs and viral antigen detection by IHC.…”

“…GI-19 field strains showed different levels of virulence to SPF chickens in experimental infections. Some strains isolated in China were nonpathogenic to SPF chicken (Yan et al, 2017), while others showed low to high pathogenicity to SPF chickens, with morbidity ranging from 40 % to 100 % and mortality ranging between 10 % and 80 % (Table 1) (Liu and Kong, 2004;Zhong et al, 2016;Yan et al, 2017;Xu et al, 2018;Li et al, 2019;Ren et al, 2019aRen et al, ,2019b. The GI-19 virus strain isolated in Malaysia was also highly virulent to SPF chickens with 100 % morbidity and 41.3 % mortality (Khanh et al, 2018).…”

“…Tissue samples of tracheas, lungs, bursa of Fabricius, spleen, liver, kidneys, proventriculus, small intestines, large intestines, cecum and cecal tonsils of the dead chickens were fixed in 10 % neutral buffered formalin, embedded in paraffin wax, and sectioned. Immunohistochemistry (IHC) was performed on serial sections prepared from the tissue samples (Ren et al, 2019a(Ren et al, ,2019b. The tissue sections were dewaxed and incubated in citrate buffer (pH 6.0) in a microwave oven at 700-800 W for 10 min and then at 200-300 W for 30 min.…”

“…IBV GI-19 viruses were initially thought to be associated with proventriculitis outbreaks (Wang et al, 1998); however, with progress in time, it was demonstrated that these viruses are responsible for respiratory signs and nephritis (Liu and Kong, 2004;Benyeda et al, 2009;Khanh et al, 2018). Morbidity caused by IBV GI-19 viruses is 100 % and mortality is usually between 5% and 70 % (Liu and Kong et al, 2004;Benyeda et al, 2009;Choi et al, 2009;Zhong et al, 2016;Khanh et al, 2018;Xu et al, 2018;Li et al, 2019;Ren et al, 2019aRen et al, ,2019bYan et al, 2019). The present report describes the isolation and investigation of a highly pathogenic IBV strain (I0305/19) belonging to the GI-19 lineage.…”

A label-free electrochemical assay for coronavirus IBV H120 strain quantification based on equivalent substitution effect and AuNPs-assisted signal amplification

“…One IBV strain, H120 strain, usually needs to be identified from other strains for immunoprophylaxis and vaccine production, for example, NNA strain. Both of them are composed of structural and nonstructural proteins [ 2 , 3 ]. The spike (S) glycoprotein is one of the major structural proteins which can be post-translationally cleaved into S1 and S2 subunits [ 4 ].…”