Genotyping of infectious bronchitis viruses identified in Canada between 2000 and 2013

Veterinary Microbiology

Zhao

Chen

et al. 2017

assessed by an S1 gene comparison and a complete genomic sequence analysis, were isolated and identified from 2009 to 2014 in China. Phylogenetic analysis, network tree, similarity plot analysis, Recombination Detection Program 4(RDP4) and sequence comparison revealed that 12 of the 20 isolates were likely the reisolated vaccine virus. One isolate, ck/CH/LSD/110857, was shown to have originated from recombination events between H120-and 4/91-like vaccine strains that did not result in changes of antigenicity and pathogenicity. The remaining seven IBV isolates were shown to have originated from recombination events between a 4/91-like vaccine strain and a GX-LY9-like virus, which were responsible for the emergence of a novel serotype. A vaccination-challenge test found that vaccination with the 4/91 vaccine strain did not provide protection against challenge with the recombinant viruses. In addition, the results showed that the recombination events between the vaccine and field strains resulted in altered genetics, serotype, antigenicity, and pathogenicity compared with those of their deduced parental viruses. The results are important not only because this virus is of economic importance to poultry industry, but also because it is important for elucidating the origin and evolution of other coronaviruses.

Section: Discussionmentioning

confidence: 69%

Genetic, antigenic, and pathogenic characteristics of avian infectious bronchitis viruses genotypically related to 793/B in China

Veterinary Microbiology

Zhao

Chen

et al. 2017

“…Of the 32 distinct viral lineages classified by Valastro et al (2016) using all publicly available S1 gene sequences, viruses in 10 lineages were found to be associated with mild to severe reductions in egg production and/or egg quality, and so-called "false layer" syndrome. It was found that no lesions could be observed in the oviducts after infection with the pathogenic 4/91 type (Benyeda et al, 2009;de Wit et al, 2011b), whereas, this genetic type was identified in Canadian outbreaks recently with predominantly respiratory disease and/or egg production problems (Martin et al, 2014), implying that viruses in the same lineage showed different affinity to reproductive tracts and this might be IBV strain specific. In this study, we did not find any obvious lesions which related to cystic oviducts in the five surviving layer chickens challenged with isolate γCoV/ck/China/I0111/14.…”

Section: Discussionmentioning

confidence: 99%

Genome characterization, antigenicity and pathogenicity of a novel infectious bronchitis virus type isolated from south China

Jiang

Zhao

Infection, Genetics and Evolution

et al. 2017

In 2014, three infectious bronchitis virus (IBV) strains, designated as γCoV/ck/China/I0111/14, γCoV/ck/China/I0114/14 and γCoV/ck/China/I0118/14, were isolated and identified from chickens suspected to be infected with IBV in Guangxi province, China. Based upon data arising from S1 sequence and phylogenetic analyses, the three IBV isolates were genetically different from other known IBV types, which represented a novel genotype (GI-29). Virus cross-neutralization tests, using γCoV/ck/China/I0111/14 as a representative, showed that genotype GI-29 was antigenically different from all other known IBV types, thus representing a novel serotype. Complete genomic analysis showed that GI-29 type viruses were closely related to and might originate from a GX-YL5-like virus by accumulation of substitutions in multiple genes. These GI-29 viral genomes are still evolving and diverging, particularly in the 3' region, although we cannot rule out the possibility of recombination events occurring. For isolate γCoV/ck/China/I0114/14, we found that recombination events had occurred between nsps 2 and 3 in gene 1 which led to the introduction of a 4/91 gene fragment into the γCoV/ck/China/I0114/14 viral genome. In addition, we found that the GI-29 type γCoV/ck/China/I0111/14 isolate was a nephropathogenic strain and high pathogenic to 1-day-old specific pathogen-free (SPF) chickens although cystic oviducts were not observed in the surviving layer chickens challenged with γCoV/ck/China/I0111/14 isolate.

“…Increased numbers of this type of virus have been isolated from chicken flocks of various bird farms in recent years in China. In addition, based on partial sequencing of the S1 gene, it appears that IBV strain 4/91 can change rapidly or that multiple introductions have occurred, e.g., the S1 genes of the 4/91 isolates were 97.8-98.6% identical to that of the IBV 4/ 91 vaccine in Canada in 2012; however, in 2013, the identity was 94.3-98.8% (Martin et al, 2014). The 4/91-like sequence from isolate ck/CH/LHLJ/140906 was more than 99.6% identical to the S1 gene of the 4/91 vaccine strain, suggesting that the vaccine was the likely source of the 4/91-like sequence.…”

Section: Discussionmentioning

confidence: 99%

Serotype shift of a 793/B genotype infectious bronchitis coronavirus by natural recombination

Zhang

Infection, Genetics and Evolution

et al. 2015

An infectious bronchitis coronavirus, designated as ck/CH/LHLJ/140906, was isolated from an infectious bronchitis virus (IBV) strain H120-vaccinated chicken flock, which presented with a suspected infectious bronchitis virus (IBV) infection. A phylogenetic analysis based on the S1 gene clustered ck/CH/LHLJ/140906 with the 793/B group; however, a pairwise comparison showed that the 5' terminal of the S1 gene (containing hypervariable regions I and II) had high sequence identity with the H120 strain, while the 3' terminal sequence was very similar to that of IBV 4/91 strain. A SimPlot analysis of the complete genomic sequence, which was confirmed by a phylogenetic analysis and nucleotide similarities using the corresponding gene fragments, suggested that isolate ck/CH/LHLJ/140906 emerged from multiple recombination events between parental IBV strains 4/91 and H120. Although the isolate ck/CH/LHLJ/140906 had slightly higher S1 amino acid sequence identity to strain 4/91 (88.2%) than to strain H120 (86%), the serotype of the virus was more closely related to that of the H120 strain (32% antigenic relatedness) than to the 4/91 strain (15% antigenic relatedness). Whereas, vaccination of specific pathogen-free chickens with the 4/91 vaccine provided better protection against challenge with ck/CH/LHLJ/140906 than did vaccination with the H120 strain according to the result of virus re-isolation. As the spike protein, especially in the hypervariable regions of the S1 domain, of IBVs contains viral neutralizing epitopes, the results of this study showed that recombination of the S1 domain resulted in the emergence of a new serotype.