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Abstract:
Cytoplasmic poly (A)-rich RNA extracted from fowl plague virus-infected cells was found to program efficiently the translation of two major peptides in the wheat germ cell-free system. These peptides have the same electrophoretic mobility, on polyacrylamide gels, as the two major virion proteins M and NP. [35S] methionine tryptic peptide analysis by one-dimensionalthin-layer ionophoresis and finger printing by two-dimensional thin-layer ionophoresis and chromatography show a high degree of similarity between the two in vitro products and the authentic viral proteins M and NP. Although virion RNA is devoid of any poly (A) sequence, it is confirmed here that the viral complementary cytoplasmic RNA contains poly (A) stretches of varying lengths. Intact purified virion was found to promote the synthesis of very low amounts of the same NP and M proteins in this cell-free system. Quantitative aspects of data would indicate that this is due to minute amounts of complementary viral RNA associated with the virion or with the virion RNA itself. In conclusion, it is shown diectly by cell-free translation of authentic viral products that the influenza virion is "negative stranded" (Baltimore, 1971), at least for its two major structural proteins.
Insights
This study shows that cytoplasmic RNA from fowl plague virus can direct the synthesis of viral proteins M and NP in a cell-free system. This confirms the negative-sense RNA genome of influenza viruses for these key structural proteins.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- Fowl plague virus (an influenza virus) is an important pathogen.
- Understanding the genetic material and protein synthesis of viruses is crucial for developing antiviral strategies.
Purpose of the Study:
- To investigate the protein-coding capacity of cytoplasmic RNA from fowl plague virus.
- To determine if viral RNA directly codes for major viral proteins M and NP.
- To confirm the strandedness of the influenza virus genome.
Main Methods:
- Wheat germ cell-free protein synthesis system.
- Polyacrylamide gel electrophoresis (PAGE) for protein analysis.
- [35S] methionine tryptic peptide mapping (one-dimensional and two-dimensional) for protein identification.
- Analysis of poly (A) sequences in viral RNA.
Main Results:
- Cytoplasmic viral RNA efficiently programmed the synthesis of two major peptides, identical in mobility to viral proteins M and NP.
- Peptide mapping confirmed high similarity between in vitro synthesized peptides and authentic M and NP proteins.
- Viral complementary cytoplasmic RNA contains poly (A) sequences, while virion RNA does not.
- Intact virions produced very low amounts of M and NP proteins in the cell-free system, likely due to associated complementary RNA.
Conclusions:
- Influenza virion RNA directly codes for viral proteins M and NP.
- The influenza virus genome is confirmed as negative-stranded for these proteins.
- The presence of poly (A) tails on complementary RNA is demonstrated.