Interrelation between Viral and Cellular DNA Synthesis in Mouse Cells Infected with the Parvovirus Minute Virus of Mice

Abstract

SUMMARYMouse fibroblasts arrested in Go by isoleucine deprivation were inoculated with the autonomous parvovirus minute virus of mice (MVM). Infected cells were released from the Go block by transfer to complete medium and their progression to and through the S phase was monitored. The onset of viral and cellular DNA synthesis coincided, suggesting that cellular factor(s) required for MVM DNA replication became available as soon as cells entered the S phase. Cellular DNA synthesis was reduced to about 60~ by MVM infection. However, this inhibition did not decrease significantly the overall rate of DNA replication in infected cells because it was compensated by concomitant viral DNA synthesis. MVM infection delayed the movement of the cells out of S phase by at least 5 h. At any time post-infection, more than 95~ of both viral and cellular DNA synthesis was sensitive to inhibition by aphidicolin. Since this drug is highly specific for cellular DNA polymerase ~, the data are consistent with a major role of this enzyme in the in vivo DNA replication of autonomous parvovirus. The assembly of 95 ~ of virus progeny particles was concomitant with a late phase of viral DNA replication which accounted for 30 ~ of the total viral DNA synthesized. The inhibition of this residual viral DNA replication by aphidicolin reduced dramatically the size of the burst of infectious particles; this observation concurs with other evidence to suggest that encapsidation is driven by a late replication event sensitive to this drug.

Minute Virus of Mice Small Nonstructural Protein NS2 Interacts and Colocalizes with the Smn Protein

“…2A). BIA was used to determine whether Smn and NS2 form a complex during MVM infection by analyzing extracts from A9 2L cells harvested 30 h postrelease from a highly synchronized MVM infection (12). Consistent with the results obtained in vitro, NS2 was .…”

Minute Virus of Mice NS1 Interacts with the SMN Protein, and They Colocalize in Novel Nuclear Bodies Induced by Parvovirus Infection

“…To determine whether SMN and NS1 form a complex during MVM infection, highly synchronized A9 2L cells (23) were harvested at 30 h postrelease. BIA was used to immunoprecipitate endogenous SMN with an anti-SMN monoclonal antibody.…”

Expression Profiling of Human Hepatoma Cells Reveals Global Repression of Genes Involved in Cell Proliferation, Growth, and Apoptosis upon Infection with Parvovirus H-1

“…Parvoviruses are incapable of inducing quiescent cells to enter S phase (66), and infection remains cryptic until host cells start a round of genomic DNA replication on their own. Once the appropriate cellular conditions are met, the virus starts its replication at the G 1 /S transition and a lytic or even productive infection can ensue (12,22), during which the infected cells get blocked in S/G 2 phase and eventually die (48, 53). The tight dependence of parvovirus replication on S-phase-associated factors accounts, in part, for the tissue specificity, oncotropism, and oncolytic activity of parvoviruses (55).…”