Feline panleukopenia

Canine parvovirus type 2 (CPV-2), which is closely related to feline pan-leukopenia virus (FPV), was described in 1978 as a new parvovirus (cited in Carmichael1). it evolved from FPV with the acquisition of five or six amino acid changes in the capsid protein2 and does not infect cats. However, during further adaptation to the dog, which most likely occurred in the raccoon, the virus underwent amino acid changes that made the mutated virus bind more efficiently to the canine cellular receptor, while retaining the abil-ity to infect cats.3,4 This led to the emer-gence of the new type, CPV-2a, which contains a series of further mutations including those at amino acid 426 of the VP2 that determine the antigenic types 2a, 2b and 2c. The parvo viruses currently circulating in dog populations worldwide (genetically and antigenically defined as types CPV-2a,-2b and-2c) can infect cats and may even cause disease.5–7 However, CPV infections of cats are rare in Europe and the USA, and the virus has only sporadically been found in diag-nostic material.6 CPV was isolated from feline peripheral blood lympho-cytes after numerous blind passages, and viral dNA was demonstrated subsequently by PCR.8 Recently, however, a case of CPV-2c infection in a cat with severe clinical disease was described in Portugal.9 during the evolution of FPV to CPV-2 with its various antigenic types, neutralising epitopes have become modified such that cross-neutralisation by FPV antisera is markedly lower against the newer viruses.10 Persistent infections with viral shedding are rare; using PCR, healthy cats have been found positive for FPV in faeces over weeks,11 and CPV-2 viruses could be isolated from the faeces of healthy cats in the UK in two shelters.12 it is unknown whether these findings are of epidemio-logical significance