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Electron microscope study of ribonucleic acid of myxoviruses
Abstract:
Intact ribonucleic acid (RNA) molecules in an extended form were extracted from purified influenza virus and observed in the electron microscope. For this study, the RNA extraction procedure and the Kleinschmidt protein monolayer technique were modified. The mean lengths of RNA from X7, X7-F1, and WSN strains of influenza virus were found to be 2.69, 2.55, and 2.37 mum, respectively. From these measurements, the corresponding estimated molecular weights would be 2.9, 2.8, and 2.5 x 10(6) daltons. X7 and WSN RNA preparations were exposed to pH 3 to disrupt intact molecules. Histograms of length measurements showed five peaks, which were interpreted to represent the five pieces of RNA reported to exist in the influenza virion. X7 RNA appeared to be more stable than WSN RNA when stored at 4 C. The profiles of histograms of incomplete virus RNA suggest that the high molecular-weight component is missing. In preliminary experiments on Newcastle disease virus RNA, molecules of various lengths were observed.
Insights
Researchers visualized intact ribonucleic acid (RNA) from influenza virus strains, measuring lengths and molecular weights. They also identified five distinct RNA segments within the virus, offering insights into viral RNA structure and stability.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- Influenza virus is a significant human pathogen.
- Understanding viral RNA structure is crucial for developing antiviral strategies.
- Previous studies suggested influenza virus contains multiple RNA segments.
Purpose of the Study:
- To visualize and measure intact ribonucleic acid (RNA) molecules from influenza virus strains.
- To determine the molecular weight and number of RNA segments within the influenza virion.
- To investigate the stability of viral RNA and compare different strains.
Main Methods:
- Modified RNA extraction and Kleinschmidt protein monolayer techniques for electron microscopy.
- Measurement of extended RNA molecule lengths.
- Acidic pH treatment to disrupt RNA molecules and analyze segment distribution.
- Preliminary experiments with Newcastle disease virus RNA.
Main Results:
- Mean RNA lengths measured for X7, X7-F1, and WSN strains were 2.69, 2.55, and 2.37 µm, respectively.
- Estimated molecular weights ranged from 2.5 to 2.9 x 10^6 daltons.
- Histograms revealed five distinct peaks, supporting the existence of five RNA segments in influenza virions.
- X7 RNA demonstrated greater stability at 4°C compared to WSN RNA.
- Incomplete virus RNA profiles indicated a missing high-molecular-weight component.
Conclusions:
- The study successfully visualized and characterized influenza virus RNA, providing direct measurements of its size and molecular weight.
- Evidence supports the model of influenza virus containing five distinct RNA segments.
- Differential stability was observed between influenza virus strains.
- Further investigation into Newcastle disease virus RNA revealed molecules of varying lengths.