Feline calicivirus: recovery of wild-type and recombinant viruses after transfection of cRNA or cDNA constructs.

The RNA genome of the vaccine strain 2024 of feline calicivirus was cloned as cDNA and analyzed by nucleotide sequencing. A full-length DNA copy of the viral genome was established and proved to be a source of infectious cRNA after in vitro transcription and RNA transfection. Virus could also be recovered when the DNA construct was introduced into cells containing phage T7 RNA polymerase that was provided by vaccinia virus MVA-T7. After insertion of the sequence encoding the green fluorescent protein into the structural protein-encoding region of the infectious cDNA clone, a defective replicon was recovered that was able to replicate autonomously and was packaged into virus particles when the structural proteins were provided in trans.