Genetic and antigenic heterogeneity among feline calicivirus isolates from distinct disease manifestations.

The capsid protein genes of five feline calicivirus (FCV) isolates associated with different disease manifestations were cloned and sequenced. The viruses represented two recent isolates from cats with chronic stomatitis, one recent isolate from a cat with acute stomatitis, one recent isolate each from a cat with acute respiratory symptoms and the classical limping syndrome strain FCV-2280. The amino acid sequences were compared with eight other published sequences and analyzed for their relationships. Phylogenetic analysis of the complete capsid protein sequences or of known antigenic regions of that protein (hypervariable regions A and E) did not group the isolates of different disease manifestations in distinct subclusters. Monoclonal antibodies (MAbs) generated against either a chronic stomatitis isolate or a recent isolate associated with respiratory symptoms were tested against a panel of 11 recent isolates and four "classical' FCV strains, covering all known disease associations. With those MAbs no obvious clustering with respect to disease manifestation could be seen. Four specific sera prepared in rabbits against our prototype isolates also failed to cluster those isolates according to the disease manifestations when examined in neutralization tests. From these antigenic and genetic analyses of the capsid protein the hypothesis of the existence of biotypes of FCV responsible for distinct disease manifestations could not be confirmed.

Detection of canine parvovirus DNA in paraffin-embedded tissues by polymerase chain reaction.

Canine Parvovirus (CPV) is seemingly a 'new' virus which suddenly appeared during the mid-1970's in an epizootic of disease in dogs. The virus is very similar to the feline panleukopenia virus (FPV), and recent studies have underlined the possible emergence of CPV as a variant of a virus from some other carnivore--possibly from FPV (Parrish, 1990). Several conserved amino-acid changes between CPV and FPV isolates have been defined by cloning and sequencing the capsid-protein gene. An alternative to cloning and sequencing the entire capsid-protein gene would be to use PCR amplification of short regions of the gene containing the appropriate variable amino-acid codons. In addition, use of PCR would also facilitate the study of virus samples which cannot be recovered as infectious agents, e.g. after having undergone formalaldehyde fixation and paraffin-embedding procedures. This study reports on the amplification of CPV DNA from 15-year-old tissue sections which have been prepared by formaldehyde or paraformaldehyde-lysine-periodate-glutaraldehyde fixation, using PCR with various primer pairs within the capsid-protein gene of CPV.