Summary auto-generated
This study sequenced and characterized a 3.8 kb region of canine calicivirus (CaCV) genome isolated from a diarrhoeic dog in Japan, spanning from the RNA polymerase gene to the poly(A) tail. The CaCV No.48 strain contains conserved calicivirus motifs (KDEL, GLPSG, and YGDD) in the polymerase region and encodes a 691-amino acid capsid protein that is proteolytically processed from a precursor form. Phylogenetic analysis comparing the polymerase, capsid, and 3' open reading frame sequences with known caliciviruses showed that CaCV is most closely related to feline calicivirus and San Miguel sea lion virus, yet represents a distinct evolutionary lineage. The genome exhibits unique features, including a 3-nucleotide spacer between the polymerase and capsid genes (compared to 2-5 nucleotides in other caliciviruses) and a notably longer 3' non-coding region (235 nucleotides). These findings indicate that CaCV constitutes a separate calicivirus genotype and potentially represents a new clade worthy of inclusion in the proposed Vesivirus genus, suggesting the existence of an undetected natural reservoir of this pathogen.
Key findings
- CaCV shares conserved calicivirus molecular motifs but shows only 44-66% sequence identity to other caliciviruses, indicating it represents a phylogenetically distinct species
- CaCV capsid protein undergoes proteolytic processing from a precursor form, similar to feline and sea lion caliciviruses, suggesting shared mechanisms among Vesivirus members
- Phylogenetic analysis places CaCV between feline calicivirus and San Miguel sea lion virus clades, supporting classification as a separate calicivirus genus
- The virus exhibits unique genomic features including a 3-nucleotide spacer between ORF1 and ORF2 and a 235-nucleotide 3' non-coding region longer than any published calicivirus sequence
This summary was generated automatically from the article PDF and is not part of the original publication. Refer to the PDF for the authoritative text.
Abstract
In recent years a wealth of data has become available about the caliciviruses that infect humans, as well as those which infect a range of animal species, notably cats, rabbits, pigs and marine animals. However, in the two decades since the earliest reports of calicivirus infection in dogs, very little has become known about the epidemiology, pathogenicity and molecular biology of the caliciviruses that may infect canines. In 1990, a canine calicivirus (CaCV) was isolated from a 2-month-old diarrhoeic domestic dog in Japan. This virus, which can be grown in cultured cells of canine origin, has the classic 'Star of David' morphology of caliciviruses, and the one major structural protein was shown to be immunogenic in dogs. In this study, a 3.8 kb region of the genome of this CaCV isolate from the RNA polymerase gene to the 3' poly(A) tail was cloned and sequenced, and phylogenetic analysis was undertaken in order to establish the relationship of CaCV to other animal and human caliciviruses. This CaCV isolate had a nucleotide sequence, genomic organization and phylogenetic position closest to, but clearly distinct from, both feline calicivirus and San Miguel sea lion virus isolates. These findings suggest that CaCV represents a new clade of animal caliciviruses, presumably as a member of the recently proposed new genus Vesivirus.