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PubMedDate not supplied

Pathogenesis of H13 nephropathogenic infectious bronchitis virus.

A nephropathogenic Massachusetts strain of infectious bronchitis virus (IBV) designated H13-IBV was isolated from the kidneys of commercial broilers. H13-IBV caused respiratory distress, depression, and diarrhea in specific-pathogen-free chickens. Gross renal lesions included pale coloration, swelling, and urate deposition. Histologic renal changes were interstitial mononuclear cell infiltration and degeneration and necrosis of tubular epithelial cells. Lesions in respiratory tissues included thickening and edema of the air sacs, congestion of the tracheal mucosa, and frothy serous exudate. Histologic tracheal lesions were deciliation, mucous gland distortion, inflammatory cell infiltration, and squamous metaplasia. Clinically, H13-IBV was highly pathogenic in birds infected at 1 day of age and mildly pathogenic in birds infected at 4 weeks of age. Kidney lesions were of marked severity only in birds infected at 1 day of age. Tracheal lesions were similar in severity in both age groups.

Animals↗

PubMed1967

Morphogenesis of avian infectious bronchitis virus and a related human virus (strain 229E).

Avian infectious bronchitis virus (IBV) and strain 229E, a virus recently recovered from patients with colds, have been shown to possess a similar distinctive morphology in negatively stained preparations. An electron microscopic study of the morphogenesis of IBV in the chorioallantoic membrane and of strain 229E in WI-38 cells was performed. In infected cells, round electron-dense particles 82 mmu in diameter were observed to form by a process of budding from membranes of the endoplasmic reticulum and cytoplasmic vesicles. The particles in IBV-infected cells were similar in size and shape to those in strain 229E-infected cells but showed certain differences in internal structure. The evidence that the particles represent virions and the implications of these findings in the classification of this virus group are discussed.

Animals↗

PubMedDate not supplied

IgM responses in chicken serum to live and inactivated infectious bronchitis virus vaccines.

Intramuscular (i.m.) administration of infectious bronchitis virus (IBV) oil-emulsion vaccine (OEV) to IBV-primed or unprimed chickens resulted in the production of zero or minimal concentrations of IBV-specific IgM in the serum, as measured by enzyme-linked immunosorbent assay of gel chromatography fractions. Live-attenuated infectious bronchitis (IB) vaccine given i.m. or by eyedrop stimulated the production of IBV-specific IgM in similar amounts following inoculation by both routes. These levels were comparable to those found in earlier studies following intranasal inoculation with a virulent strain of IBV and confirm that the detection of IBV-specific IgM is a valuable aid to the diagnosis of recent infection. As expected, administration of live-attenuated IB vaccines i.m. or by eyedrop protected the respiratory tract against challenge with virulent virus 24 days later; however, OEV given i.m. did not.

Animals↗

PubMedDate not supplied

Viral pathogenesis of a nephrotropic infectious bronchitis virus isolated from commercial pullets.

Infectious bronchitis was diagnosed in 3-to-4-week-old pullets from an outbreak in a commercial flock in California. The disease was characterized by head swelling, watery discharge from the eyes and nostrils, and urates in kidneys. Mortality ranged from 1.8% to 12.5% per week. The isolation of a coronavirus from a suspension of pooled kidneys from clinically ill chickens at the fifth passage in 10-day-old chicken embryos, gross and histologic renal lesions, and seroconversion by enzyme-linked immunosorbent assay in inoculated birds suggested that the virus isolated was a nephrotrophic strain of infectious bronchitis virus (IBV). The virus isolate was found to be a previously unrecognized serotype, based on virus neutralization tests performed in embryonated chicken eggs. Nephropathogenicity of the IBV isolate was confirmed by inoculation of the viral isolate into specific-pathogen-free chicks and demonstration of renal lesions. The isolation of nephrotropic strains of IBV has not been reported previously from poultry in California.

Animals↗

PubMed2006

Neither the RNA nor the proteins of open reading frames 3a and 3b of the coronavirus infectious bronchitis virus are essential for replication.

Gene 3 of infectious bronchitis virus is tricistronic; open reading frames (ORFs) 3a and 3b encode two small nonstructural (ns) proteins, 3a and 3b, of unknown function, and a third, structural protein E, is encoded by ORF 3c. To determine if either the 3a or the 3b protein is required for replication, we first modified their translation initiation codons to prevent translation of the 3a and 3b proteins from recombinant infectious bronchitis viruses (rIBVs). Replication in primary chick kidney (CK) cells and in chicken embryos was not affected. In chicken tracheal organ cultures (TOCs), the recombinant rIBVs reached titers similar to those of the wild-type virus, but in the case of viruses lacking the 3a protein, the titer declined reproducibly earlier. Translation of the IBV E protein is believed to be initiated by internal entry of ribosomes at a structure formed by the sequences corresponding to ORFs 3a and 3b. To assess the necessity of this mechanism, we deleted most of the sequence representing 3a and 3b to produce a gene in which ORF 3c (E) was adjacent to the gene 3 transcription-associated sequence. Western blot analysis revealed that the recombinant IBV produced fivefold less E protein. Nevertheless, titers produced in CK cells, embryos, and TOCs were similar to those of the wild-type virus, although they declined earlier in TOCs, probably due to the absence of the 3a protein. Thus, neither the tricistronic arrangement of gene 3, the internal initiation of translation of E protein, nor the 3a and 3b proteins are essential for replication per se, suggesting that these proteins are accessory proteins that may have roles in vivo.

Animals↗

PubMed1984

Sequential development of humoral immunity and assessment of protection in chickens following vaccination and challenge with avian infectious bronchitis virus.

Chicks without specific maternal antibody to avian infectious bronchitis virus were vaccinated intranasally at two weeks old with a live H120 vaccine and a proportion revaccinated with a live H52 vaccine at 15 weeks. Groups of these birds were then challenged intratracheally with the Massachusetts M41 strain at varying intervals and their humoral antibody responses monitored by neutralisation and haemagglutination-inhibition tests. Protection was assessed by the presence of tracheal ciliostasis four days after challenge and was shown to correlate completely with histopathological findings and immunofluorescence microscopy. Chicks were protected by H120 alone up to 12 weeks old and, following revaccination with H52, up to between 30 and 50 weeks. The antibody responses following challenge became increasingly enhanced as the vaccinal antibody titres declined. The results are discussed in relation to previous reports and the response to vaccination against infectious bronchitis virus of chickens in commercial flocks.

Animals↗

PubMedDate not supplied

Identification of seven isolants of infectious bronchitis virus by interference with the B-1 isolant of Newcastle disease virus.

Seven isolants of infectious bronchitis virus (IBV) interfered with the development of hemagglutinins (HA) by the B-1 isolant of Newcaslte disease virus (NDV) in eggs previously inoculated with these IBV isolants. The I50 [defined as the minimum amount of IBV needed to produce, upon inoculation in embryonating chicken eggs (ECE), HA interference in 50% of these ECE reioculated 10 hr later with 10(2,41 EID50 (HA) of the B-1 strain of NDV] was less than 1 EID50. The interference was considered specific for IBV because if could be eliminated by addition of homologous anti-IBV serum. Furthermore, three other common poultry viruses (laryngotracheitis, fowlpox, and CELO viruses) did not interfere with NDV. In view of its sensitivity, specificity, and simplicity of performance, the IBV-NDV interference test appears to have considerable potential as a diagnostic test for IBV under field conditions.

Coronaviridae↗

PubMed1999

Sequence analysis of the turkey coronavirus nucleocapsid protein gene and 3' untranslated region identifies the virus as a close relative of infectious bronchitis virus.

The 3' end of the turkey coronavirus (TCV) genome (1740 bases) including the nucleocapsid (N) gene and 3' untranslated region (UTR) were sequenced and compared with published sequences of other avian and mammalian coronaviruses. The deduced sequence of the TCV N protein was determined to be 409 amino acids with a molecular mass of approximately 45 kDa. The TCV N protein was identical in size and had greater than 90% amino acid identity with published N protein sequences of infectious bronchitis virus (IBV); less than 21% identity was observed with N proteins of bovine coronavirus and transmissible gastroenteritis virus. The 3' UTR showed some variation among the three TCV strains examined, with two TCV strains, Minnesota and Indiana, containing 153 base segments which are not present in the NC95 strain. Nucleotide sequence identity between the 3' UTRs of TCV and IBV was greater than 78%. Similarities in both size and sequence of TCV and IBV N proteins and 3' UTRs provide additional evidence that these avian coronaviruses are closely related.

3' Untranslated Regions↗

PubMed2005

Generation of a recombinant avian coronavirus infectious bronchitis virus using transient dominant selection.

A reverse genetics system for the avian coronavirus infectious bronchitis virus (IBV) has been described in which a full-length cDNA, corresponding to the IBV (Beaudette-CK) genome, was inserted into the vaccinia virus genome following in vitro assembly of three contiguous cDNAs [Casais, R., Thiel, V., Siddell, S.G., Cavanagh, D., Britton, P., 2001. Reverse genetics system for the avian coronavirus infectious bronchitis virus. J. Virol. 75, 12359-12369]. The method has subsequently been used to generate a recombinant IBV expressing a chimaeric S gene [Casais, R., Dove, B., Cavanagh, D., Britton, P., 2003. Recombinant avian infectious bronchitis virus expressing a heterologous spike gene demonstrates that the spike protein is a determinant of cell tropism. J. Virol. 77, 9084-9089]. Use of vaccinia virus as a vector for the full-length cDNA of the IBV genome has the advantage that modifications can be made to the IBV cDNA using homologous recombination, a method frequently used to insert and delete sequences from the vaccinia virus genome. We describe the use of homologous recombination as a method for modifying the Beaudette full-length cDNA, within the vaccinia virus genome, without the requirement for in vitro assembly of the IBV cDNA. To demonstrate the feasibility of the method we exchanged the ectodomain of the Beaudette spike gene for the corresponding region from IBV M41 and generated two recombinant infectious bronchitis viruses (rIBVs) expressing the chimaeric S protein, validating the method as an alternative way for generating rIBVs.

Animals↗

PubMed2004

Identification of a novel nephropathogenic infectious bronchitis virus in Israel.

A novel infectious bronchitis variant, designated as IS/885/00, associated with nephritis, was isolated from outbreaks in 23 broiler farms in Israel. The virus was first identified by reverse transcriptase-polymerase chain reaction and showed a distinct restriction fragment length polymorphism pattern from previously described Israeli isolates. Sequence analysis of the S1 gene and the deduced amino acid sequence revealed 97.2% protein similarity to genotype IS/ 720/99 and 71.6% similarity to the vaccine strain H120, the only strain permitted for use in this country. A database search in GenBank revealed a closely related isolate from Egypt, Egypt/Beni-Seug/01, with 96.6% similarity. Other published nephropathogenic infectious bronchitis virus strains/isolates shared less than 77% similarity with IS/885/00. A vaccine protection test in specific-pathogen-free chicks indicated 91% protection to the trachea and only 25% protection to the kidneys in vaccinated birds challenged with IS/885/00.

Amino Acid Sequence↗

PubMed1984

Effects of subtype variations in the Holland strain of infectious bronchitis virus when applied as a vaccine.

Massachusetts-type infectious bronchitis viruses (IBV) designated H120, from three sources, have been evaluated as vaccines. Significant subtype variations were observed with the different vaccines based upon challenge virus infection and typical IB lesions induced where homologous and heterologous serotypes were used. In numerous cases, there was little agreement between challenge virus recovery from the respiratory tract and the presence or absence and severity of IB lesions. The study indicates that histopathological observations provide a sensitive, reliable indicator of the immune response to IB vaccination and augment the use of challenge virus isolation attempts. The data suggest that the use of the latter criterion alone was insufficient in evaluating IB immunity. The study also demonstrated that IB vaccine strains, although labeled similarly, varied in their immunogenic properties. Manipulation of infectious bronchitis virus (IBV) and other factors should be considered when obtaining and employing vaccine strains from different sources. Complete characterization of IBV vaccine strains used commercially should be stressed together with an appropriate labeling of each.

Animals↗

PubMed1990

Selection of variants of avian infectious bronchitis virus showing tropism for different organs.

Avian infectious bronchitis virus strain Kagoshima-34 isolated from the kidneys of a chicken that died of nephrosis/nephritis lost its nephropathogenicity during intratracheal passage in SPF chickens. The resultant virus acquired stronger respirotropism but reduced tropism for kidneys. On the other hand strain Tottori-2 isolated from the trachea of a chicken suffering from severe respiratory disease did not lose its respirotropism after serial intravenous passage in SPF chickens. The serological properties of the passaged virus were investigated by virus neutralisation test. The antibody titres of both strains of virus fluctuated with progressive passage. The serological properties of the virus isolated from respiratory organs were not necessarily the same as those of the isolates made from the kidneys.

Animals↗

PubMedDate not supplied

[Biological properties of the chick infectious bronchitis virus isolated in Russia].

A field chick infectious bronchitis virus (IBV) was isolated from the pathological material on chick embryos. The nucleotide sequence of the S1 gene was determined and comparatively analyzed with some sequences of this gene of foreign and Russian vaccine strains and isolates. A cross-neutralization test using sera to various IBV seroptypes was performed. The isolate was shown to antigenically differ from the reference strains. Bioassay was carried out, by using one-day chicks and the immunogenic properties of the virus were investigated.

Animals↗

PubMedDate not supplied

Redesign of primer and application of the reverse transcriptase-polymerase chain reaction and restriction fragment length polymorphism test to the DE072 strain of infectious bronchitis virus.

Diagnosis of the DE072 strain of infectious bronchitis virus (IBV) by the reverse transcriptase-polymerase chain reaction (RT-PCR) and restriction fragment length polymorphism (RFLP) serotype identification test was not possible because the primer used in the RT-PCR did not amplify the S1 gene of the DE072 strain. The 3' end of the polymerase gene and the 5' end of the S2 gene of the DE072 strain were sequenced and compared with the forward and reverse RT-PCR primers, respectively. A 2-bp mismatch at the 3' end of the reverse primer was found. On the basis of these data, a degenerate primer that could amplify the S1 gene of the DE072 strain as well as eight other serotypes of the virus was synthesized. In addition, we were able to differentiate the DE072 strain from all of the other IBV strains examined by RFLP analysis of the RT-PCR product.

Animals↗

PubMed2006

Genotypic and phenotypic characterization of the California 99 (Cal99) variant of infectious bronchitis virus.

The California 99 (Cal99) variant of infectious bronchitis virus (IBV) was first recovered in 1999 from vaccinated broiler chicken flocks in Central California. The S1 hypervariable region of Cal99 genome was most closely related to Arkansas (Ark) serotype viruses. In this study, the complete genome of Cal99 was sequenced, and the structural protein genes were compared with those of commonly used IBV vaccines as well as those of isolates from naturally occurring outbreaks in different parts of the world, to elucidate potential sources of genetic material. Based on sequence comparison, the prototype Cal99 virus is similar to the apathogenic ArkDPI virus, except in the S1 gene and stretches of sequence in the S2 and M structural protein genes, which are more related to Connecticut (Conn) and Massachusetts (Mass) strain viruses, respectively. We speculate that these two fragments came from a Conn and a Mass virus, respectively, and were incorporated into a virus largely derived from ArkDPI. Since Ark, Conn and Mass strains have been simultaneously used as live vaccines in California, both point mutations and recombination among vaccine strains may have contributed to the emergence of the Cal99 variant virus. Analysis of the structural protein genes of six Cal99 isolates demonstrated that viruses of this serotype may differ substantially in the non-S1 structural genes. Finally, we performed a challenge study with Cal99 and demonstrated that the virus causes late-onset respiratory disease, with a severity comparable to that of the M41 IBV challenge strain.

Amino Acid Sequence↗

PubMed1976

Heterogeneity of infectious bronchitis virus grown in eggs.

Egg-grown infectious bronchitis virus, strain Beaudette, was concentrated and centrifuged on sucrose density gradients to separate the virus into five peaks with densities of 1.144, 1.160, 1.172, 1.191 and 1.218 g/cm3. All peaks retained infectivity, complement fixation activity and were labelled with 3H-uridine. Morphologically the densest peak consisted of very large virus particles and amorphous material, the other peaks consisted of mainly intact particles although small differences in size and pleomorphism were seen. Polyacrylamide gel electrophoresis of material from the density gradient peaks revealed four major polypeptides and at least 10 minor polypeptides. The proportions of the polypeptides were approximately similar for all peaks with the exception of the densest peak in which the major polypeptides were greatly reduced. The four major polypeptides had approximate molecular weights of 1. 52,000, 2. 45,000, 3. 34,000, 4. 32,000. The major polypeptides 1 and 4 were shown to be glycosylated as were two of the minor polypeptides.

Animals↗

PubMed2026

The Q653R substitution in the spike protein is associated with attenuation of a GVI-1 infectious bronchitis virus strain.

The GVI-1 genotype of infectious bronchitis virus (IBV) has become increasingly prevalent in Asia. In this study, a highly pathogenic GVI-1 strain (GVI-1-WT) was attenuated by 110 serial passages in embryonated chicken eggs, yielding an attenuated strain (GVI-1-E110). Comparative genomic analysis identified two amino acid substitutions, S523I, Q653R and a nine-amino-acid truncation in the spike (S) protein. To evaluate the contribution of the two point mutations to virulence attenuation, recombinant viruses carrying Q653R and S523I substitutions were generated using a reverse genetics system based on the GVI-1-WT strain as the backbone. Their replication and pathogenicity were assessed in embryonated eggs and specific pathogen-free chickens. The Q653R substitution was associated with reduced viral replication in embryonated chicken eggs and pathogenicity in specific pathogen-free chickens, whereas the S523I mutation alone showed a limited effect but enhanced attenuation when combined with Q653R. However, the attenuation phenotype of the recombinant viruses did not fully recapitulate that of the passaged strain GVI-1-E110, suggesting that additional mutations, including the identified truncation and mutations in replicase-associated genes outside the S protein, may also contribute to virulence attenuation. This study indicates that spike protein mutations are involved in the attenuation of GVI-1 IBV strains, and provides insights into the molecular basis of IBV attenuation during serial passage. Further studies are required to elucidate the underlying mechanisms and to evaluate their potential relevance for vaccine development.

GVI-1 genotype↗

PubMed2006

Infectious bronchitis virus serotypes in poultry flocks in Jordan.

Infectious bronchitis virus (IBV) causes respiratory disease in chickens all over the world. IBV has many serotypes that do not confer cross protection against each other. Hemagglutination inhibition (HI) test has been used to determine the serotypes of IBV as a substitute to the more laborious virus neutralization test and the more sophisticated restriction endonuclease digestion or sequencing of the S1 gene. In Jordan, no previous studies have been carried out to determine the involvement of IBV in respiratory disease in chickens, or the serotypes of IBV that possibly exist. In this study, serum from different chicken flocks (n=20) that suffered from respiratory disease were tested for IBV antibodies using commercial IBV antibody ELISA at time of the initial signs of the respiratory disease and repeated on serum samples from the same flocks 10-14 days later. ELISA titer for IBV increased in 14 out of 20 flocks (70%) after 10-14 days of the initial signs of the respiratory disease and this indicates a recent exposure to IBV. The second serum samples from these 14 flocks were further examined against a panel of five IBV antigens (Ark, Conn, DE-072, JMK, and Mass) by HI test to determine the serotype(s) of IBV they have been exposed to. The HI test results indicated that the exposure of some of these flocks were to Ark, DE-072, and Mass like serotypes. However, the HI titers against the antigens used in this study were relatively similar in 10 out of the 14 flocks (71%) and the serotype of IBV that these flocks were exposed to could not be determined and the possible causes of this are discussed.

Animals↗