Recombination of Feline calicivirus within an endemically infected cat colony

To understand the evolution of the family Caliciviridae, the persistence of Feline calicivirus (FCV) was studied within an endemically infected cat colony. Polymerase and capsid sequences were analysed for 34 FCV isolates obtained over a 4 year period. Initially, the colony was infected with one strain of virus, but a second distinct strain was later identified. Subsequently, the emergence of a recombinant virus was observed, containing elements of both of the strains circulating within the colony. The recombination event mapped close to the ORF1/ORF2 junction. This is consistent with recombination in other caliciviruses, suggesting a common mechanism within this family. This is the first report of recombination within the genus Vesivirus in the family Caliciviridae and the first time that a recombination event has been observed where the parental strains have also been identified.