GENETIC AND ANTIGENIC HETEROGENEITY AMONG FELINE CALICIVIRUS ISOLATESFROM DISTINCT DISEASE MANIFESTATIONS

The capsid protein genes of five feline calicivirus (FCV) isolates ass ociated with different disease manifestations were cloned and sequence d. The viruses represented two recent isolates from cats with chronic stomatitis, one recent isolate from a cat with acute stomatitis, one r ecent isolate each from a cat with acute respiratory symptoms and the classical limping syndrome strain FCV-2280. The amino acid sequences w ere compared with eight other published sequences and analyzed for the ir relationships. Phylogenetic analysis of the complete capsid protein sequences or of known antigenic regions of that protein (hypervariabl e regions A and E) did not group the isolates of different disease man ifestations in distinct subclusters. Monoclonal antibodies (MAbs) gene rated 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 respe ct to disease manifestation could be seen. Four specific sera prepared in rabbits against our prototype isolates also failed to cluster thos e isolates according to the disease manifestations when examined in ne utralization tests. From these antigenic and genetic analyses of the c apsid protein the hypothesis of the existence of biotypes of FCV respo nsible for distinct disease manifestations could not be confirmed. (C) 1997 Elsevier Science B.V.