Parvoviruses depend on initiation of host cell division for their replication. Undefined parvoviral proteins
have been detected in Purkinje cells of the cerebellum after experimental feline panleukopenia virus
(FPV) infection of neonatal kittens and in naturally occurring cases of feline cerebellar hypoplasia. In this
study, a parvoviral protein in the nucleus of Purkinje cells of kittens with cerebellar hypoplasia was
shown by immunoprecipitation to be the FPV viral capsid protein VP2. In PCR-confirmed, FPV-associated
feline cerebellar hypoplasia, expression of the FPV VP2 protein was demonstrated by immunohistochemistry
in Purkinje cell nuclei in 4/10 cases and expression of the FPV non-structural protein NS1 was demonstrated
in Purkinje cell nuclei in 5/10 cases. Increased nuclear ERK1 expression was observed in several
Purkinje cells in 1/10 kittens. No expression of the G1 and S mitotic phase marker proliferating cell
nuclear antigen (PCNA) was evident in Purkinje cell nuclei. These results support the hypothesis that
FPV is able to proceed far into its replication cycle in post-mitotic Purkinje cells.