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Productive and non-productive phases during long-term persistence of influenza C virus
M Marschall1, C Böswald, A Schuler
1Abteilung für Virologie, Technische Universität München, Germany.
Abstract:
Persistent infection with a variant of influenza C/Ann Arbor/1/50 virus in MDCK cells has been previously reported. However, the precise molecular mechanism of persistence is still unknown. We show that the release of active progeny virus, as tested for by haemagglutination and acetylesterase profiles, does not take place in freshly seeded MDCK cells. Productive virus replication occurs simultaneously with massive production of structural proteins as shown by immunoprecipitation and immunofluorescence. PCR for the HEF structural protein-encoding segment 4 revealed that positive-sense RNA is present only during virus multiplication whereas negative-sense RNA appears to be constantly detectable. In this study we give initial evidence that influenza C virus can persist in the form of its genomic minus strand RNA, and plus strand transcription, protein synthesis and virus replication remain restricted to productive phases.
Insights
Influenza C virus persists via its genomic minus strand RNA in MDCK cells. Productive replication and protein synthesis are restricted to specific phases, with active progeny release absent in fresh cell cultures.
Area of Science:
- Virology
- Molecular Biology
- Cell Biology
Background:
- Persistent infection with influenza C virus (ICV) in Madin-Darby canine kidney (MDCK) cells is known.
- The molecular mechanisms underlying this persistent infection remain largely unelucidated.
Purpose of the Study:
- To investigate the molecular mechanisms of persistent influenza C virus infection in MDCK cells.
- To determine the state of viral RNA and replication during persistent infection.
Main Methods:
- Infection of MDCK cells with influenza C/Ann Arbor/1/50 virus.
- Assays for viral release (haemagglutination, acetylesterase activity).
- Immunoprecipitation and immunofluorescence for protein synthesis.
- Polymerase chain reaction (PCR) for viral RNA detection (positive-sense and negative-sense).
Main Results:
- Active progeny virus release was not detected in freshly seeded MDCK cells.
- Productive virus replication and massive structural protein production occurred simultaneously.
- Negative-sense viral RNA was constantly detectable, while positive-sense RNA was only present during multiplication.
Conclusions:
- Influenza C virus can persist in MDCK cells primarily as its genomic minus strand RNA.
- Plus strand transcription, protein synthesis, and replication are confined to productive phases.
- This suggests a unique persistence strategy for influenza C virus, distinct from active virion release.