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Host range restriction of parainfluenza virus growth occurs at the level of virus genome replication
1Department of Virology and Molecular Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.
Abstract:
To illuminate the molecular basis for host range restriction of parainfluenza virus replication, we have examined the types of virus macromolecules produced during abortive infection of nonpermissive MDBK cells with human parainfluenza virus type 1 (hPIV1). While these cells do not support production of hPIV1 virus, they can be infected by hPIV1 as evidenced by accumulation of intracellular viral NP and HN proteins. HPIV1 is also able to drive transcription of a synthetic analog of Sendai virus (SV) genome RNA transfected into virus-infected MDBK cells. In contrast to transcription, hPIV1 genome replication does not occur in MDBK cells. Intracellular full-length genome RNA was detected only in trace amounts 2 days after infection, and was undetectable 4 days after infection. Full-length antigenome (+) sense RNA was not detectable. Nucleocapsid complexes failed to accumulate in the cytoplasm of nonpermissive cells, and no detectable nucleocapsids were released into the medium as virus particles. The data indicate that defective vRNA synthesis and/or nucleocapsid formation is responsible for the inability of hPIV1 to grow in MDBK cells. Our data also show that hPIV1 is capable of providing all helper functions for packaging SV synthetic genome analogs into infectious particles, but these SV-specific RNAs encapsidated with hPIV1 proteins are in turn not replicated by SV proteins. These results suggest that functional protein-protein interactions between parainfluenza virus strains have more stringent requirements than do protein-RNA interactions.
Insights
Human parainfluenza virus type 1 (hPIV1) cannot replicate in MDBK cells due to defective viral RNA synthesis and nucleocapsid formation. Protein interactions are key for parainfluenza virus replication, more so than protein-RNA interactions.
Area of Science:
- Virology
- Molecular Biology
- Cell Biology
Background:
- Host range restriction limits viral infections.
- Parainfluenza viruses cause significant human respiratory illness.
- Understanding hPIV1 replication is crucial for developing antivirals.
Purpose of the Study:
- To investigate the molecular mechanisms of human parainfluenza virus type 1 (hPIV1) host range restriction.
- To identify the viral macromolecules produced during abortive hPIV1 infections in nonpermissive cells.
- To determine the role of viral RNA synthesis and nucleocapsid formation in hPIV1 replication.
Main Methods:
- Abortive infection of MDBK cells with hPIV1.
- Analysis of intracellular viral protein and RNA synthesis.
- Transcription and replication assays using synthetic Sendai virus (SV) genome analogs.
Main Results:
- hPIV1 infection of MDBK cells leads to NP and HN protein accumulation but not viral replication.
- hPIV1 drives transcription of SV genome analogs but not replication.
- Defective viral RNA synthesis and/or nucleocapsid formation prevents hPIV1 growth in MDBK cells.
- hPIV1 can package SV RNAs, but these are not replicated by SV proteins.
Conclusions:
- Defective vRNA synthesis and nucleocapsid formation are responsible for hPIV1 host range restriction.
- Protein-protein interactions between parainfluenza virus strains are critical and have stringent requirements.
- Functional protein-RNA interactions are less restrictive than protein-protein interactions for parainfluenza virus replication.