Identification and molecular characterization of a novel serotype infectious bronchitis virus (GI-28) in China

Abstract

Avian infectious bronchitis coronavirus (IBV) is a major poultry pathogen. A characteristic feature of IBV is the occurrence of many different strains belonging to different serotypes, which renders complete control of the disease by vaccination a challenging task due to the poor cross-protection between different serotypes. In this study, based on the results of S1 sequence analysis and virus cross-neutralization tests, IBV strain ck/CH/LGX/111119 was found to be genetically and antigenically different from other known IBV types, representing not only a novel genotype, but also a novel serotype (designated as GI-28). Viruses belonging to this novel serotype have been isolated from several regions in China in recent years, suggesting endemic circulation of the serotype in various geographic locations in China. Further studies by complete genomic analysis showed that strain ck/CH/LGX/111119 may have originated from recombination events involving LX4 genotype IBVs and an as-yet-unidentified IBV donating a S1 gene, or from the result of accumulation of mutations and selections, especially in the S1 gene, from a LX4 genotype virus. ck/CH/LGX/111119 is a nephropathogenic strain, although it had broader tissue tropism (respiratory, digestive, urinary, and reproductive tracts) among chickens challenged at one day old. Infection of the oviducts with ck/CH/LGX/111119 found in this study may have severe implications because the virus will likely induce the occurrence of false layers.

Characterization of the complete genome, antigenicity, pathogenicity, tissue tropism, and shedding of a recombinant avian infectious bronchitis virus with a ck/CH/LJL/140901-like backbone and an S2 fragment from a 4/91-like virus

“…Recently, numerous IBV strains have been identified and new genotypes/serotypes have emerged from existing viruses via point mutations, insertions, and deletions in the viral genome, especially in the S1 subunit of the spike protein gene. At least six IBV genotypes together comprise 34 distinct viral lineages and a number of unassigned interlineage recombinants have been recognized worldwide according to a simple and repeatable phylogeny-based classification system that uses the complete nucleotide sequence of the S1 gene and an unambiguous and rationale lineage nomenclature for the assignment of IBVs (Valastro et al, 2016;Chen et al, 2017;Jiang et al, 2017).…”

Analysis of antigenicity and pathogenicity reveals major differences among QX-like infectious bronchitis viruses and other serotypes

“…The inaccuracy of the coronavirus RNA-dependent RNA polymerase and high frequency of genetic changes in IBV (e.g., gene insertion, mutation, deletion, and reconstruction), promote the emergence of new variant strains, genotypes and serotypes of IBV, and these are continuously reported (Cavanagh et al, 1986;Chen et al, 2017;Yan et al, 2016;Zhao et al, 2016). IBV immunity is serotype-specific, and Mass-type vaccines (H120) can be ineffective against infection with different IBV isolates in China (Chen et al, 2017;Sun et al, 2011;Zhao et al, 2015). Therefore, the continuous testing of pathogenicity in new isolates, epidemic serotype determination, and typing new IBV strains remains crucial for better epidemiological understanding and control of IB in regions and/or countries.…”

Novel genotype of infectious bronchitis virus isolated in China

“…The full S1 gene sequence generated in this study was subjected to BLAST searches using the National Center for Biotechnology Information database, and then analyzed phylogenetically using a dataset consisting of 73 sequences ( Supplemental Table 1), including representative sequences for each genotype and lineage, as recently recommended (Valastro et al, 2016;Chen et al, 2017;Jiang et al, 2017), and the GX-NN130021 strain, which was closely related to I0636/16 by BLAST analysis. The S1 gene sequences of the IBV strain I0636/16 and the selected viruses were aligned using ClustalW, and phylogenetic analysis was carried out using Mega version 6.0 software (http://www.…”

“…Antisera against the viruses H120, 4/91, LDL/091022, LDL/97I, LSC/99I, LGX/111119, and I0111/14 Chen et al, 2017;Jiang et al, 2017) were used in this study. Antisera against strains I0725/17 and I0636/16 were produced in this study following a standard protocol .…”