Biochemical and antigenic characterization of feline herpesvirus-1-like isolates from dogs

The DNA and polypeptide patterns of feline herpesvirus-1 (FHV-1), a virus usually associated with feline respiratory infections, were compared to those of five herpesvirus isolates from dogs. These canine isolates had been shown to be antigenically similar to FHV-1 by cross neutralization tests. DNA from FHV-1 (C-27 strain) and each canine isolate was digested with either Bam HI, Eco R 1 or Sal I and analyzed on 0.8 per cent agarose gels. The restriction digest patterns of the canine isolates were nearly identical to C-27 for all three restriction enzymes. Interestingly, all of the canine isolates showed a small extension of the largest Bam HI fragment (14.5 kb) that was not present in the C-27 strain. Bam HI digested FHV-1 DNA from clinical cases in cats had digest patterns that were very similar to the canine isolates and also showed an extension of the 14.5 kb fragment. Southern blotting experiments revealed that DNA from the canine isolates has extensive homology to C-27 DNA. SDS-PAGE analysis of radiolabeled polypeptides from C-27 and the canine isolates showed identical virion-associated polypeptide profiles. In addition, a goat anti-FHV-1 antiserum precipitated three glycoprotein antigens from the canine isolates with migration patterns that were identical to the three major antigenic glycoproteins found on C-27. Hind III and Eco R1 digestion patterns of canine herpesvirus DNA showed no similarity to C-27 DNA. In addition, canine herpesvirus DNA had no homology to C-27 DNA under the stringent conditions used.