Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Comparative Study
. 2008 Feb;82(4):2013-24.
doi: 10.1128/JVI.01694-07. Epub 2007 Nov 28.

Infectious bronchitis viruses with a novel genomic organization

Karim Mardani  1 , Amir H Noormohammadi, Peter Hooper, Jagoda Ignjatovic, Glenn F Browning
Affiliations
Comparative Study

Infectious bronchitis viruses with a novel genomic organization

Karim Mardani et al. J Virol. 2008 Feb.

Abstract

A number of novel infectious bronchitis viruses (IBVs) were previously identified in commercial poultry in Australia, where they caused significant economic losses. Since there has been only limited characterization of these viruses, we investigated the genomic and phenotypic differences between these novel IBVs and other, classical IBVs. The 3' 7.5 kb of the genomes of 17 Australian IBV strains were sequenced, and growth properties of 6 of the strains were compared. Comparison of sequences of the genes coding for structural and nonstructural proteins revealed the existence of two IBV genotypes: classical and novel. The genomic organization of the classical IBVs was typical of those of other group III coronaviruses: 5'-Pol-S-3a-3b-E-M-5a-5b-N-untranslated region (UTR)-3'. However, the novel IBV genotype lacked either all or most of the genes coding for nonstructural proteins at the 3' end of the genome and had a unique open reading frame, X1. The gene order was either 5'-Pol-S-X1-E-M-N-UTR-3' or 5'-Pol-S-X1-E-M-5b-N-UTR-3'. Phenotypically, novel and classical IBVs also differed; novel IBVs grew at a slower rate and reached lower titers in vitro and in vivo and were markedly less immunogenic in chicks. Although the novel IBVs induced histopathological lesions in the tracheas of infected chicks that were comparable to those induced by classical strains, they did not induce lesions in the kidneys. This study has demonstrated for the first time the existence of a naturally occurring IBV genotype devoid of some of the genes coding for nonstructural proteins and has also indicated that all of the accessory genes are dispensable for the growth of IBV and that such viruses are able to cause clinical disease and economic loss. The phylogenic differences between these novel IBVs and other avian coronaviruses suggest a reservoir host distinct from domestic poultry.

PubMed Disclaimer

Figures

FIG. 1.
FIG. 1.
Comparison of the nucleotide sequence of the region coding for gene 3 (3a, 3b, and E) of classical and novel IBV strains with that of the reference strain Beaudette (GenBank accession number AJ311317). Underlined bases are the putative start and stop codons. The putative TRSs, which are located upstream of the start codon, are boxed. Missing bases or deletions are indicated with dashes (-). Unshaded sequences upstream and downstream of ORF X1 in the novel IBVs are the 3′ end of the S gene and noncoding region, respectively. formula image, ORF X1; formula image, 3a gene; formula image, 3b gene; formula image, 3c gene.
FIG. 1.
FIG. 1.
Comparison of the nucleotide sequence of the region coding for gene 3 (3a, 3b, and E) of classical and novel IBV strains with that of the reference strain Beaudette (GenBank accession number AJ311317). Underlined bases are the putative start and stop codons. The putative TRSs, which are located upstream of the start codon, are boxed. Missing bases or deletions are indicated with dashes (-). Unshaded sequences upstream and downstream of ORF X1 in the novel IBVs are the 3′ end of the S gene and noncoding region, respectively. formula image, ORF X1; formula image, 3a gene; formula image, 3b gene; formula image, 3c gene.
FIG. 2.
FIG. 2.
Comparison of the nucleotide sequence of the region coding for gene 5 (5a and 5b) of classical and novel IBV strains with that of the reference strain Beaudette (GenBank accession number AJ311317). Underlined bases are the putative start and stop codons. The TRSs, which are located upstream from the start codons, are boxed. Missing bases or deletions are indicated with dashes (-). formula image, 5a gene; formula image, 5b gene.
FIG. 3.
FIG. 3.
(A) Phylogenic tree inferred from the 3′ 7.5-kb nucleotide sequences of 17 Australian IBV strains and the Beaudette strain using the DNAml program in the PHYLIP package. (B) Comparison of the structures of the 3′ 7.5 kb of the genome of the “classical” and “novel” Australian IBVs strains.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Casais, R., M. Davies, D. Cavanagh, and P. Britton. 2005. Gene 5 of the avian coronavirus infectious bronchitis virus is not essential for replication. J. Virol. 798065-8078. - PMC - PubMed
    1. Casais, R., B. Dove, D. Cavanagh, and P. Britton. 2003. Recombinant avian infectious bronchitis virus expressing a heterologous spike gene demonstrates that the spike protein is a determinant of cell tropism. J. Virol. 779084-9089. - PMC - PubMed
    1. Cavanagh, D. 2005. Coronaviridae: a review of coronaviruses and toroviruses, p. 1-54. In A. Schmidt, M. H. Wolff, and O. Weber (ed.), Coronaviruses with special emphasis on first insights concerning SARS. Birkhauser Verlag, Berlin, Germany.
    1. Cavanagh, D. 2003. Severe acute respiratory syndrome vaccine development: experiences of vaccination against avian infectious bronchitis coronavirus. Avian Pathol. 32567-582. - PMC - PubMed
    1. Cavanagh, D., P. J. Davis, J. H. Darbyshire, and R. W. Peters. 1986. Coronavirus IBV: virus retaining spike glycopolypeptide S2 but not S1 is unable to induce virus-neutralizing or haemagglutination-inhibiting antibody, or induce chicken tracheal protection. J. Gen. Virol. 671435-1442. - PubMed

Publication types

LinkOut - more resources

  NODES
twitter 2