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In vivo effect of three transformation-defective mutants of subgroup C avian sarcoma viruses
Abstract:
Three transformation-defective mutants derived from avian sarcoma viruses of subgroup C, td PR-RSV-C (Vogt), td B77 (Toyoshima) and td daPR-RSV-C (isolated in our laboratory), were injected intravenously into 12-day-old chicken embryos and intraperitoneally into newly-hatched chickens. Both Brown Leghorn chickens and F1 hybrids of two inbred chicken lines (C X I) were used. Haematological changes and formation of visible tumours were evaluated in animals kept for 8-9 months. All three td mutants produced in a significant proportion of intraembryonally injected animals haematological disorders which, in certain cases, resembled the anaemic and proliferative type of erythroblastosis. Most conspicuous symptoms of erythroblastosis were seen after td daPR-RSV-C which also gave rise to two sarcomas, containing transforming viruses. The possible character of oncogenic information retained or acquired by the TD mutants is discussed.
Insights
Three avian sarcoma virus mutants caused hematological disorders resembling erythroblastosis in chickens. One mutant, td daPR-RSV-C, also induced sarcomas, indicating retained oncogenic potential.
Area of Science:
- Virology
- Oncology
- Immunology
Background:
- Avian sarcoma viruses (ASVs) are retroviruses known to cause tumors in chickens.
- Transformation-defective (td) mutants of ASVs have lost the ability to transform cells in vitro but may retain oncogenic potential in vivo.
- Understanding the oncogenic capacity of td mutants is crucial for deciphering viral oncogenesis.
Purpose of the Study:
- To investigate the in vivo oncogenic potential of three transformation-defective avian sarcoma virus mutants (td PR-RSV-C, td B77, and td daPR-RSV-C).
- To evaluate the hematological changes and tumor formation induced by these td mutants in chicken embryos and newly-hatched chickens.
Main Methods:
- Intravenous injection of td PR-RSV-C, td B77, and td daPR-RSV-C into 12-day-old chicken embryos.
- Intraperitoneal injection of the same td mutants into newly-hatched Brown Leghorn and F1 hybrid chickens.
- Monitoring of hematological parameters and observation for visible tumor formation over an 8-9 month period.
Main Results:
- All three td mutants induced hematological disorders in a significant proportion of intraembryonally injected animals.
- These disorders resembled the anemic and proliferative types of erythroblastosis.
- The td daPR-RSV-C mutant exhibited the most conspicuous erythroblastosis symptoms and also induced two sarcomas containing transforming viruses.
Conclusions:
- Transformation-defective avian sarcoma virus mutants can retain significant in vivo oncogenic potential, inducing hematological disorders and tumors.
- The td daPR-RSV-C mutant demonstrated a notable capacity for inducing both erythroblastosis and sarcomas, suggesting retained or acquired oncogenic information.
- These findings highlight the complex interplay between viral genetics and host response in avian oncogenesis.