High Genetic Diversity of the Immunodominant Region of the Feline Calicivirus Capsid Gene in Endemically Infected Cat Colonies

• Published in: Virus genes 2003-10, Vol.27 (2), p.145-155
• Main Authors: Radford, Alan D, Dawson, Susan, Ryvar, Ruth, Coyne, Karen, Johnson, Deborah R, Cox, Michael B, Acke, Els F J, Addie, Diane D, Gaskell, Rosalind M
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Antigenic Variation - genetics; Base Sequence; Caliciviridae Infections - epidemiology; Caliciviridae Infections - veterinary; Caliciviridae Infections - virology; Calicivirus, Feline - genetics; Calicivirus, Feline - immunology; Calicivirus, Feline - isolation & purification; Capsid Proteins - genetics; Capsid Proteins - immunology; Cat Diseases - epidemiology; Cat Diseases - virology; Cats; Cell Line; Endemic Diseases - veterinary; Genetic Variation; Immunodominant Epitopes; Molecular Sequence Data; Mutation, Missense; Phylogeny; Prevalence; Reverse Transcriptase Polymerase Chain Reaction; RNA, Viral - genetics; RNA, Viral - isolation & purification; Selection, Genetic; Sequence Analysis
• ISSN: 0920-8569; 1572-994X
• DOI: 10.1023/A:1025772409539

Feline calicivirus (FCV) is an important pathogen of domestic cats. In this study, we have determined the genetic diversity of FCV within four geographically separate colonies of endemically infected cats by sequencing the immunodominant and variable region E of the capsid gene. Comparison of isolates between colonies and between unrelated published sequences gave nucleotide distance values of 26–35% and 22–40%, respectively and suggested each colony was infected with a distinct virus strain. Comparison of isolates within individual endemically infected colonies showed nucleotide distance variability of 0–16%. This was greater than distances previously reported for epidemiologically related isolates from cases of acute disease (0–5%) and was consistent with the evolution of FCV from a single distinct ancestor sequence in each colony. The pattern of nucleotide substitutions generating the observed intra-colony diversity was associated with strong evidence for positive selection acting on immunodominant regions of the FCV capsid protein. We suggest that endemically infected colonies of cats may be important generators of genetic diversity for FCV and that this may ultimately lead to the generation of new strains.