Summary auto-generated
Respiratory syncytial virus (RSV) causes respiratory disease in multiple species including humans, cattle, and sheep. This study sequenced the G glycoprotein gene from ovine (sheep) RSV to determine its genetic relationship with bovine and human RSV strains. The ovine RSV G gene contained 838 nucleotides encoding a 263-amino acid protein. Nucleotide sequence comparison revealed only 73% identity with bovine RSV, and the deduced amino acid sequence showed 60% identity. However, the two viruses shared similar hydropathy profiles and conserved cysteine residues, suggesting structural similarities despite sequence divergence. Analysis of intergenic regions flanking the G gene showed 64% and 57% identity between ovine and bovine RSV. The cytoplasmic and transmembrane domains of the G proteins were highly conserved (89% and 78% identity), while the extracellular domain showed lower identity (53%). Antigenic testing demonstrated cross-reactivity between ovine and bovine RSV. Based on the level of G gene sequence divergence (40%), the authors propose classifying ovine and bovine RSV as two subgroups of a broader ungulate RSV category, analogous to the A and B subgroups recognized in human RSV.
Key findings
- Ovine RSV G gene shows 73% nucleotide identity and 60% amino acid identity with bovine RSV, sufficient difference to warrant classification as separate subgroups of ungulate RSV
- The extracellular domain of ovine RSV G protein is less conserved (53% identity) than cytoplasmic and transmembrane domains (89% and 78%), suggesting selective immune pressure on surface-exposed regions
- Intergenic regions between genes show lower conservation (57-64% identity) compared to coding sequences, consistent with patterns observed between human RSV subgroups
- Five cysteine residues in the G protein are conserved at identical positions across ovine, bovine, and human RSV strains, indicating structural conservation despite sequence divergence
- Ovine and bovine RSV strains show antigenic cross-reactivity, with polyclonal antibodies to bovine RSV reacting with ovine RSV proteins including the G protein
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Abstract
Respiratory syncytial virus (RSV) has been isolated from sheep suffering from respiratory tract disease. Since the greatest differences between bovine RSV and human RSV are found on the attachment G protein, we have determined the nucleotide and deduced amino acid sequences of the G gene of ovine RSV. The latter contained 838 nucleotides and had a major open reading frame encoding a protein of 263 residues, and shared 73% nucleotide sequence identity with that of bovine RSV. The deduced amino acid sequence of the ovine RSV G protein showed only 60% amino acid identity with the G protein of bovine RSV. Despite the low level of identity, there were similarities in the predicted hydropathy profiles of the G proteins of ovine and bovine RSV. The intergenic sequences for the SH-G and G-F gene junctions of ovine RSV showed 64 and 57% identity respectively with the corresponding regions of the bovine RSV. Our results indicate that ovine and bovine RSV might be classified as two subgroups of an ungulate RSV.