Virulence of CPV-2a and -2b in Cats
The pathogenicity of CPV-2a and 2b in cats remains debatable. Mochizuki et al. reported the isolation of CPV-2a from a cat manifesting clinical signs of feline panleukopenia . The detection of CPV-2a/2b-type DNA sequences from the cheetahs with chronic diarrhea and enteritis or the tiger with anorexia and diarrhea  strongly suggests CPV-2a's and CPV-2b's pathogenic potential in large felids. In sharp contrast, recent studies using SPF cats experimentally infected with CPV-2a or CPV-2b showed no or slight illness, such as mild lymphopenia, in the infected animals [31,33,37,38]. Moreover, the fact that many CPV-2a- and CPV-2b-type viruses were isolated from clinically healthy cats [11,30,35,39] seems to indicate their relatively low pathogenicity.
At present, this discrepancy remains to be resolved. Note, however, that the experimental infection of SPF cats with FPLV generally leads to mild disease [23,24]. In this regard, the study reported by Goto et al.  is intriguing. These researchers compared the clinical signs of five SPF and four conventional cats experimentally infected with CPV-2a. The infected five SPF cats showed neither clinical signs nor leukopenia through the observation period, while depression (four cases), vomiting (two), diarrhea (one) , and severe leukopenia (four) were observed in the four conventional cats. One cat died 4 days after infection . These data indicate that the illness from CPV-2a/2b infection highly depends on the general condition of the cats before infection.
Emerging Infectious Diseases. 2002;8(4) © 2002 Centers for Disease Control and Prevention (CDC)
Cite this: Feline Host Range of Canine parvovirus: Recent Emergence of New Antigenic Types in Cats - Medscape - Apr 01, 2002.