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Analysis of Pichinde arenavirus transcription and replication in human THP-1 monocytic cells
S J Polyak1, S Zheng, D G Harnish
1Department of Pathology and Biology, McMaster University, Hamilton, Ontario, Canada.
Abstract:
Human promonocytic THP-1 cells were previously shown to be nonpermissive for Pichinde virus (PV) replication unless the cells were induced to differentiate to macrophages by stimulation with phorbol ester (PMA) (J. Virol. 65, 3575, 1991). The restriction did not involve receptor modulation, virus binding, nor internalization of virus but a requirement for a host cell function in PV replication was observed in that the phorbol ester effect required protein kinase C activation and was inhibited by actinomycin D. In this report we demonstrate that PV S RNA genomes, antigenomes, GPC mRNA and NP mRNA are expressed at high levels in PMA treated THP-1 cells but at significantly lower levels or not at all in untreated cells. We have also determined that degradation of input viral S RNA does not account for decreased PV RNA synthesis in the undifferentiated cells. This suggests that the restriction of PV replication in THP-1 cells is a post-penetration event which precedes transcription of viral mRNAs and replication of viral genomes and supports a role for differentiation-specific host cell factors early in PV replication.
Insights
Pichinde virus (PV) replication in THP-1 cells is restricted until cells differentiate into macrophages. This restriction occurs post-entry and requires host cell factors, impacting viral RNA synthesis.
Area of Science:
- Virology
- Cell Biology
- Molecular Biology
Background:
- Human promonocytic THP-1 cells are nonpermissive for Pichinde virus (PV) replication.
- Differentiation into macrophages using phorbol ester (PMA) renders THP-1 cells permissive to PV.
Purpose of the Study:
- To investigate the mechanism of PV replication restriction in undifferentiated THP-1 cells.
- To identify the stage at which PV replication is blocked in non-differentiated cells.
Main Methods:
- Comparison of PV RNA and mRNA expression levels in PMA-treated versus untreated THP-1 cells.
- Assessment of viral RNA degradation in undifferentiated cells.
Main Results:
- PMA treatment significantly increases the expression of PV S RNA genomes, antigenomes, GPC mRNA, and NP mRNA.
- PV replication restriction in undifferentiated cells is not due to degradation of input viral S RNA.
- The restriction point occurs post-penetration and prior to viral mRNA transcription and genome replication.
Conclusions:
- PV replication in THP-1 cells is regulated by a post-penetration host cell function.
- Cell differentiation, likely involving protein kinase C activation, is crucial for overcoming this restriction.
- Differentiation-specific host factors play a role early in the PV replication cycle.