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Murine type-C virus group-specific antigens: interstrain immunochemical, biophysical, and amino acid sequence
Abstract:
The 30,000-molecular-weight internal protein, p30, was purified from seven strains of mouse type-C viruses. The individual p30's showed variation in isoelectric points and also intrastrain heterogeneity. The individual p30's could be distinguished by peptide map and quantitative complement fixation techniques with relatedness estimates of >95%. Amino terminal sequence analysis showed variability at position 4 for several p30's with complete homology otherwise through 24 residues. The intrastrain heterogeneity in p30 isoelectric points could not be explained by common contaminants, as shown by peptide mapping, and is more likely based on post-transcriptional modifications. These data provide a chemical basis for the recently described type-specific immunological properties of individual p30's.
Insights
Mouse type-C virus internal protein p30 exhibits variations in isoelectric points and amino acid sequences. These differences, likely due to post-transcriptional modifications, explain the protein
Area of Science:
- Virology
- Molecular Biology
- Immunology
Background:
- Murine retroviruses, specifically type-C viruses, possess an internal structural protein known as p30.
- The p30 protein plays a role in viral structure and is associated with type-specific immunological properties.
Purpose of the Study:
- To chemically characterize the p30 protein from various mouse type-C virus strains.
- To investigate the basis for intrastrain heterogeneity observed in p30.
- To correlate chemical properties of p30 with its known immunological specificities.
Main Methods:
- Purification of p30 protein from seven strains of mouse type-C viruses.
- Isoelectric focusing to assess charge heterogeneity.
- Peptide mapping to compare protein structures.
- Quantitative complement fixation assays for relatedness estimation.
- Amino terminal sequence analysis.
Main Results:
- Purified p30 proteins displayed variations in isoelectric points and intrastrain heterogeneity.
- Peptide mapping and complement fixation indicated high relatedness (>95%) among p30 variants.
- Amino terminal sequencing revealed conserved homology across 24 residues, with variability noted at position 4.
- Intrastrain heterogeneity was not attributed to contaminants and suggested post-transcriptional modification.
Conclusions:
- The study provides a chemical basis for the type-specific immunological properties of mouse type-C virus p30.
- Post-transcriptional modifications are likely responsible for the observed intrastrain heterogeneity in p30.
- Detailed chemical analysis of p30 aids in understanding retroviral diversity and antigenicity.