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Characterization of papillomavirus polypeptides from bovine cutaneous fibropapillomas
G Della Torre1, M Muttini, D Ballinari
1Division of Experimental Oncology, Istituto Nazionale per lo Studio e la Cura dei Tumori, Milan, Italy.
Abstract:
Virions of bovine papilloma virus (BPV) were isolated from a pool of cutaneous bovine fibropapillomas and purified by CsCl gradient centrifugation. SDS-PAGE revealed several polypeptides with an Mr ranging from 76K to 19K. Western blot analysis of the viral isolate identified additional polypeptides when a rabbit anti-BPV serum was used, but only the main capsid component of 57K when a rabbit antiserum raised against human papillomavirus was used. The viral preparation was then 125I-labelled and further purified by gel filtration. SDS-PAGE of immunoprecipitates of the anti-BPV serum with different fractions from the chromatographic column revealed the polypeptides of 76K, 57K and 28K to be viral structural components. The 28K polypeptide, not previously characterized, was shown to be composed of several molecular forms, migrating over a pH range of 3.5 to 4.6 when analysed by two-dimensional PAGE. Following SDS-PAGE performed under non-reducing conditions, the 28K and 76K polypeptides and the main capsid component of 57K appeared to be linked by disulphide bridges to form hetero- or homopolymers.
Insights
Researchers isolated bovine papilloma virus (BPV) virions and identified key structural proteins, including a novel 28K polypeptide. These components form polymers linked by disulfide bridges, advancing our understanding of BPV structure.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- Bovine papilloma virus (BPV) causes fibropapillomas in cattle.
- Understanding BPV virion structure is crucial for developing antiviral strategies.
Purpose of the Study:
- To characterize the structural polypeptides of BPV virions.
- To identify novel viral components and their interactions.
Main Methods:
- Isolation and purification of BPV virions via CsCl gradient centrifugation.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis.
- Radioiodination (125I-labelling), gel filtration, and two-dimensional PAGE.
Main Results:
- SDS-PAGE identified polypeptides ranging from 76K to 19K.
- Western blot analysis with anti-BPV serum revealed 76K, 57K, and 28K polypeptides as viral structural components.
- A novel 28K polypeptide, existing in multiple molecular forms (pH 3.5-4.6), was characterized.
- The 28K, 76K, and 57K polypeptides form hetero- or homopolymers via disulfide bridges.
Conclusions:
- BPV virions are composed of at least three major structural polypeptides: 76K, 57K (major capsid protein), and a novel 28K protein.
- These proteins interact through disulfide bonds to form polymeric structures.
- Further characterization of the 28K polypeptide is warranted.