Feline panleukopenia virus (FPV) is an autonomous parvovirus. It is the prototype of a
number of closely related parvoviruses which were isolated from various carnivores such as
dogs, mink, raccoons, raccoon dogs, foxes and other canids (Parrish, 1990). The viruses were
initially named after the hosts from which they had been isolated. Current taxonomy defines
canine parvovirus and feline panleukopenia virus as one single taxonomic entity (Tattersall,
2006), but in the present guidelines, FPV refers to parvovirus in cats.
FPV is known to infect cats and other members of the Felidae, as well as raccoons, mink, and
foxes (Steinel et al., 2001). In dogs, FPV replication was seen only in lymphoid tissues, such
as thymus, spleen and bone marrow, but not in the gut, and the virus is not shed (Truyen and
Parrish, 1992).
In 1978 a new parvovirus, very closely related to FPV, was first described in dogs
(Carmichael, 2005). It was named canine parvovirus type 2 (CPV-2), to distinguish it from
another parvovirus isolated from dogs in 1970, which is now called canine minute virus
(CaMV). CPV-2 is believed to have evolved from FPV by acquiring 5 or 6 amino acid
changes in the capsid protein gene (Truyen, 1999). Interestingly, CPV-2 was no longer able to
infect cats. However, during subsequent further adaptation to the canine host, the amino acid
changes that had enabled the new virus to better bind to the canine cellular receptor also
resulted in its ability to infect cats (Hueffer and Parrish, 2003). The parvoviruses now
circulating in the dog populations worldwide and which can be genetically and antigenically
defined as the types CPV-2a, -2b, and “–2c”, are able to infect cats and may even cause
disease (Truyen et al., 1995, 1996; Mochizuki et al., 1996). However, feline CPV infections
are rare in Europe and the USA, and CPV is found only sporadically in diagnostic material
(Truyen et al., 1996). CPV was isolated from feline peripheral blood lymphocytes after
numerous blind passages, and viral DNA was demonstrated by polymerase chain-reaction
(PCR), as reported in a study from Taiwan (Ikeda et al., 2000).
During the evolution from FPV to CPV-2 with its various antigenic types, neutralizing
epitopes have been affected such that cross-neutralization by FPV antisera is markedly lower
against the new viruses (Truyen, 1997).
FPV is a non-enveloped, single-stranded DNA virus which is highly resistant to physical
factors and chemical substances. In contaminated environments, it may remain infectious for
weeks or even months (Uttenthal et al., 1999). Diseased carnivores shed virus at high titres
(up to 109 TCID50 per gram of faeces), and virus quickly accumulates in affected shelters and
catteries. As it is highly contagious, susceptible animals may still become infected, even after
a seemingly thorough disinfection of the premises. It is therefore recommended that only
successfully vaccinated kittens and cats should enter such an environment.
Although few data on FPV prevalence are available, particularly breeding catteries and rescue
shelters are at risk (Addie et al., 1998; Cave et al., 2002).