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Structure of simian virus 40 DNA in primary and derived mouse tumors
Abstract:
Primary tumors induced by Simian Virus 40 (SV40) in nude mice, lines derived from them, and subsequent transplanted tumors were analyzed as to the state of the viral DNA. It was found that SV40 DNA is present only as integrated molecules, each tumor having a different integration pattern; all tumors were SV40 T-antigen positive by immunofluorescence. One tumor and its derivatives in vitro and in vivo have maintained a single integration structure consisting of a head-to-tail arrangement of a molecule slightly larger than whole-length viral DNA (approximately equal to 1.1). This tumor expresses a full-sized T-antigen and a Mr 54,000 host-associated protein.
Insights
Simian Virus 40 (SV40) DNA integrates into tumors in nude mice, with varying patterns. One tumor line consistently shows a single, head-to-tail SV40 DNA integration, expressing T-antigen and a host protein.
Area of Science:
- Virology
- Oncology
- Molecular Biology
Background:
- Simian Virus 40 (SV40) is a DNA tumor virus known to induce tumors in various animal models.
- Understanding the state and integration of viral DNA within tumor cells is crucial for comprehending viral oncogenesis.
Purpose of the Study:
- To investigate the integration patterns of Simian Virus 40 (SV40) DNA in primary and transplanted tumors in nude mice.
- To characterize the molecular features of a specific SV40-induced tumor with a stable viral DNA integration.
Main Methods:
- Analysis of viral DNA integration in SV40-induced tumors and derived cell lines using molecular techniques.
- Immunofluorescence staining to detect SV40 T-antigen expression.
- Characterization of viral DNA structure and associated host proteins.
Main Results:
- SV40 DNA was found exclusively as integrated molecules in all analyzed tumors, with distinct integration patterns per tumor.
- All tumors tested were positive for SV40 T-antigen expression.
- One specific tumor and its derivatives maintained a single, stable integration site with a head-to-tail arrangement of SV40 DNA (approx. 1.1 units).
- This tumor expressed a full-length T-antigen and a 54,000 Mr host-associated protein.
Conclusions:
- SV40 DNA integration is a consistent feature of SV40-induced tumorigenesis in this model.
- Tumorigenesis can be driven by integrated viral DNA, even with varying integration sites.
- A specific SV40-induced tumor model with a defined integration structure offers a valuable system for studying viral oncogenesis and gene expression.