Related Experiment Videos
Respiratory syncytial virus matrix protein associates with nucleocapsids in infected cells
R Ghildyal1, J Mills1, M Murray1
1Children's Virology Research Unit, Macfarlane Burnet Institute for Medical Research and Public Health, PO Box 254, Yarra Bend Road, Fairfield, Victoria 3078, Australia1.
Abstract:
Little is known about the functions of the matrix (M) protein of respiratory syncytial virus (RSV). By analogy with other negative-strand RNA viruses, the M protein should inhibit the viral polymerase prior to packaging and facilitate virion assembly. In this study, localization of the RSV M protein in infected cells and its association with the RSV nucleocapsid complex was investigated. RSV-infected cells were shown to contain characteristic cytoplasmic inclusions. Further analysis showed that these inclusions were localization sites of the M protein as well as the N, P, L and M2-1 proteins described previously. The M protein co-purified with viral ribonucleoproteins (RNPs) from RSV-infected cells. The transcriptase activity of purified RNPs was enhanced by treatment with antibodies to the M protein in a dose-dependent manner. These data suggest that the M protein is associated with RSV nucleocapsids and, like the matrix proteins of other negative-strand RNA viruses, can inhibit virus transcription.
Insights
The respiratory syncytial virus matrix protein (RSV M) is found in cytoplasmic inclusions and binds to viral ribonucleoproteins. This association suggests RSV M protein inhibits viral transcription.
Area of Science:
- Virology
- Molecular Biology
Background:
- The function of the matrix (M) protein in respiratory syncytial virus (RSV) is largely unknown.
- By analogy with other negative-strand RNA viruses, the M protein is hypothesized to inhibit viral polymerase before packaging and aid in virion assembly.
Purpose of the Study:
- To investigate the localization of the RSV M protein within infected cells.
- To determine the association of the RSV M protein with the viral nucleocapsid complex.
Main Methods:
- RSV-infected cells were analyzed to identify M protein localization.
- Immunoprecipitation was used to assess the co-purification of M protein with viral ribonucleoproteins (RNPs).
- The effect of anti-M protein antibodies on RNP transcriptase activity was measured.
Main Results:
- RSV-infected cells exhibited characteristic cytoplasmic inclusions containing M protein, along with N, P, L, and M2-1 proteins.
- The M protein was found to co-purify with RSV RNPs.
- Treatment of purified RNPs with antibodies against the M protein dose-dependently enhanced transcriptase activity.
Conclusions:
- The RSV M protein is associated with RSV nucleocapsids.
- The M protein likely plays a role in regulating RSV transcription, potentially by inhibiting the viral polymerase, similar to matrix proteins of other negative-strand RNA viruses.