Apoptosis induced by H-1 parvovirus infection was investigated in C6 rat glioblastoma cells and in newborn rats. Apoptotic changes, such as chromatin condensation, the appearance of apoptotic nuclear bodies and oligonucleosomal DNA ladders, were observed in infected C6 cells 2 days after infection. Inhibitor assay results suggest that a caspase-3-dependent apoptosis activation pathway is induced by H-1 virus infection in C6 cells. Observations made in vivo revealed that the number of apoptotic cells increased in the infected cerebellum, coinciding with known virus infection sites.

"Orphan" parvovirus (OPV) infection in laboratory mice and rats was serologically surveyed for 465 mouse sera and 271 rat sera collected from 1986 to 1987 and from 1993 to 1996 in Japan. The results suggest that parvovirus infection is rare in mice but common in rats (positive rate: 13-22%) and that most putative viruses were OPVs. OPV is therefore considered to already have been harbored for at least ten years in Japan.