Variation in the spike protein of the 793/B type of infectious bronchitis virus, in the field and during alternate passage in chickens and embryonated eggs.

The degree of variation exhibited within the 793/B serotype (also known as 4/91 and CR88 serotypes) was investigated with nine French and 10 British isolates, collected between 1985 and 1994. The S1 part (1644 nucleotides) of the spike protein gene of the first known isolate of this serotype, FR/CR85131/85, had 95.9% to 97% nucleotide identity with the other isolates.

Subtype B avian metapneumovirus resembles subtype A more closely than subtype C or human metapneumovirus with respect to the phosphoprotein, and second matrix and small hydrophobic proteins.

Avian metapneumovirus (aMPV) subtype B (aMPV/B) nucleotide sequences were obtained for the phosphoprotein (P), second matrix protein (M2), and small hydrophobic protein (SH) genes. By comparison with sequences from other metapneumoviruses, aMPV/B was most similar to subtype A aMPV (aMPV/A) relative to the US subtype C isolates (aMPV/C) and human metapneumovirus (hMPV). Strictly conserved residues common to all members of the Pneumovirinae were identified in the predicted amino acid sequences of the P and M2 protein-predicted amino acid sequences.

Coronaviruses from pheasants (Phasianus colchicus) are genetically closely related to coronaviruses of domestic fowl (infectious bronchitis virus) and turkeys.

Reverse-transcriptase polymerase chain reactions (RT-PCRs) were used to examine RNA extracted from mouth/nasal swabs from pheasants exhibiting signs of respiratory disease. The oligonucleotides used were based on sequences of infectious bronchitis virus (IBV), the coronavirus of domestic fowl. A RT-PCR for the highly conserved region II of the 3' untranslated region of the IBV genome detected a coronavirus in swabs from 18/21 estates.

Detection of a coronavirus from turkey poults in Europe genetically related to infectious bronchitis virus of chickens.

Intestinal contents of 13-day-old turkey poults in Great Britain were analysed as the birds showed stunting, unevenness and lameness, with 4% mortality. At post mortem examination, the main gross features were fluid caecal and intestinal contents. Histological examination of tissues was largely unremarkable, apart from some sections that showed crypt dilation and flattened epithelia.

Infectious bronchitis virus vaccine interferes with the replication of avian pneumovirus vaccine in domestic fowl.

Experiments were performed in chickens to ascertain whether application of infectious bronchitis (IB) H120 vaccine had an effect on the replication of an attenuated avian pneumovirus (APV) strain, using as indicators virus detection, humoral antibody responses and clinical protection against in vivo APV challenge. A preliminary experiment demonstrated that pharyngeal swabs were as efficient for recovery of APV as were buccal cavity swabs, and that either site was superior to swabbing the nasal cavity. APV was detected to a similar extent by both a reverse transcriptase-polymerase chain reaction (RT-PCR) and virus isolation; therefore, RT-PCR was used in subsequent experiments.

Longitudinal field studies of infectious bronchitis virus and avian pneumovirus in broilers using type-specific polymerase chain reactions.

In longitudinal studies, 13 flocks were swabbed twice each week for the life of the flock (up to 46 days). The swabs were analyzed by type-specific reverse transcriptase polymerase chain reactions. Massachusetts type vaccinal infectious bronchitis virus (IBVs), applied at the hatchery, were usually maximal during the first week, as expected and, notably, remained detectable for 3 to 4 weeks, occasionally longer.

Co-circulation of four types of infectious bronchitis virus (793/B, 624/I, B1648 and Massachusetts).

Eighteen isolates of infectious bronchitis virus (IBV) from Italy and Poland in 1997 to 1998 were comprehensively analysed by serum haemagglutination inhibition and virus neutralization tests, and by type-specific polymerase chain reactions and spike protein S1 gene sequencing. Four types of IBV (793/B, 624/I, B1648 and Massachusetts) were detected in Italy, while the presence of 793/B was confirmed in Poland. This showed that not only were four types of IBV co-existing within a single year, but also that several types of IBV have persisted in Europe for many years (at least 13 to 14 years for types B1648 and 793/B).

Does IBV change slowly despite the capacity of the spike protein to vary greatly?

We have sequenced that part of the spike protein (S) gene which encodes the aminoterminal and most variable quarter (hypervariable region, HVR) of the S1 subunit of 28 isolates of the 793/B (also known as CR88 and 4/91) serotype of infectious bronchitis virus (IBV) and the whole of S1 for nine of them. The isolates were from France and Britain between the years 1985 (first isolation) and 1996. The maximum nucleotide and amino acid differences between the first isolate and the others were 4.

Towards the routine application of nucleic acid technology for avian disease diagnosis.

The use of nucleic acid technology (polymerase chain reaction, probing, restriction fragment analysis and nucleotide sequencing) in the study of avian diseases has largely been confined to fundamental analysis and retrospective studies. More recently these approaches have been applied to diagnosis and what one might call real-time epidemiological studies on chickens and turkeys. At the heart of these approaches is the identification and characterisation of pathogens based on their genetic material, RNA or DNA.

Expression of bacteriophage T7 RNA polymerase in avian and mammalian cells by a recombinant fowlpox virus.

The bacteriophage T7 RNA polymerase gene was integrated into the fowlpox virus genome under the control of the vaccinia virus early/late promoter, P7.5. The recombinant fowlpox virus, fpEFLT7pol, stably expressed T7 RNA polymerase in avian and mammalian cells, allowing transient expression of transfected genes under the control of the T7 promoter.

Investigation of the control of coronavirus subgenomic mRNA transcription by using T7-generated negative-sense RNA transcripts.

The subgenomic mRNAs of the coronavirus transmissible gastroenteritis virus (TGEV) are not produced in equimolar amounts. We have developed a reporter gene system to investigate the control of this differential subgenomic mRNA synthesis. Transcription of mRNAs by the TGEV polymerase was obtained from negative-sense RNA templates generated in situ from DNA containing a T7 promoter.

Characterization of the transmissible gastroenteritis virus (TGEV) transcription initiation sequence. Characterization of TGEV TIS.

The ability of the TGEV transcription initiation sequence (TIS) to produce subgenomic RNAs was investigated by placing a reporter gene, chloramphenicol acetyltransferase (CAT) under the control of either the mRNA 6 or the mRNA 7 TISs. Both constructs only produced CAT in TGEV infected cells and the amount of CAT produced from the mRNA 7 TIS was less than from the mRNA 6 TIS. Mutations were made within and around the TISs and the effect on CAT production assayed.

The cloning and sequencing of the virion protein genes from a British isolate of porcine respiratory coronavirus: comparison with transmissible gastroenteritis virus genes.

Previous analysis of porcine respiratory coronavirus (PRCV) mRNA species showed that mRNAs 2 and 3 were smaller than the corresponding transmissible gastroenteritis virus (TGEV) mRNA species (Page et al. (1991) J. Gen.

Sequence comparison of the 5' end of mRNA 3 from transmissible gastroenteritis virus and porcine respiratory coronavirus.

Analysis of porcine transmissible gastroenteritis virus (TGEV) and porcine respiratory coronavirus (PRCV) mRNA species indicated a deletion in mRNA 3 of PRCV. Polymerase chain reaction (PCR) was used to clone the 5' end of mRNA 3 from PRCV for comparison with the equivalent region in TGEV. Small deletions were observed within and around the PRCV sequence equivalent to the putative open reading frame (ORF) ORF-3a identified in TGEV.