Characterization of a recombinant coronavirus infectious bronchitis virus with distinct S1 subunits of spike and nucleocapsid genes and a 3′ untranslated region

Abstract

An infectious bronchitis virus (IBV), ck/CH/LZJ/111113, was isolated from a H120-vaccinated chicken which showed disease suspected of IBV infection. Neutralization testing showed that ck/CH/LZJ/111113 was distinct from either the Chinese predominant IBV LX4-type or Mass-type vaccine strains. Phylogenetic analysis confirmed that ck/CH/LZJ/111113 is of the 4/91 type; however, further extensive analyses of full-length genomes identified occurrence of recombination events. Therefore, ck/CH/LZJ/111113 originated from the recombination events between ck/CH/LDL/091022- and 4/91-like strains at three switch sites located upstream of the spike (S) glycoprotein gene, and the 3' ends of S1 and nuceocapsid (N) genes, respectively. The difference of serotypes and tissue tropisms in kidneys between ck/CH/LZJ/111113 and ck/CH/LDL/091022 may have been contributed by the uptake of the S1 gene by a ck/CH/LDL/091022-like virus from a 4/91-like strain. This recombination event took place at the 3' end of the N gene and the 3' untranslated region may account for differences in replication efficiency in tissues of chickens inoculated by the two viruses.

Molecular and antigenic characteristics of Massachusetts genotype infectious bronchitis coronavirus in China

“…The results in this study showed that the ck/CH/LHB/111172 and ck/CH/LSD/111219 isolates experienced multiple recombination events and two breakpoints were identified. The recombination events from which the two viruses resulted can be explained by two models, similar to that of ck/CH/LZJ/111113 (Liu et al, 2013). For the remaining three viruses, ck/CH/LDL/110931, ck/CH/LHB/ 130573, and ck/CH/LHB/130598, only one breakpoint was identified.…”

“…Total viral RNA was isolated from 200 ml of infected allantoic fluids using TRIzol reagent (Invitrogen, Carlsbad, CA, USA) according to the manufacturer's instructions. The complete genomes of 31 Mass genotype of IBV strains were amplified and sequenced as previously described (Liu et al, 2013). The obtained nucleotide sequences were manually edited, assembled, and analyzed using the Clustal W method available in the BioEdit software package (version 7.0.3.0., available at: http://www.mbio.…”

“…To further identify the recombinant events, the BLASTN program (Liu et al, 2013) was used to search GenBank for IBV sequences that were homologous to those of the five IBV isolates, ck/CH/LHB/111172, ck/CH/LSD/111219, ck/CH/LHB/130598, ck/CH/ LDL/110931, and ck/CH/LHB/130573. The Similarity Plot of the complete genomic sequences (Lole et al, 1999), the nucleotide similarities and phylogenetic trees for each deduced recombinant fragment were analyzed with the MEGA 5.0 program (Schierup and Hein, 2000).…”

Origin and evolution of LX4 genotype infectious bronchitis coronavirus in China

“…Overlapping fragments of the genome of the 110 IBV strains were obtained through RT-PCR using primer sets based on the conserved regions in the genome among most of the IBV strains (Liu et al, 2013). A one-step method was adopted using PrimeScript TM One Step RT-PCR kit Ver.2 (TaKaRa) and the following 25/L mixture: 12.5/L of 2 Â 1 step Buffer, 7.5/L of PrimeScript I step Enzyme Mix, 15 nmol each of downstream and upstream primers and 3/L of template RNA.…”

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

“…Since then, some other strains of this virus also have been isolated and identified (Xu et al, 2007;Han et al, 2009). Interestingly, we recently isolated a virulent, nephropathogenic 793/B type virus, which was found to have emerged from a recombination event between the 4/91 vaccine strain and an LX4 type (also known as QX-like) virus (Liu et al, 2013). More recently, we isolated another 793/B genotype virus, which also originated from a recombinant event that resulted in a serotype shift .…”