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Abstract:
Retroviruses received widespread attention in the past not only because they caused tumors in animals and, perhaps, in man, but also because they served as useful tools to elucidate molecular mechanisms involved in the control of eukaryotic gene expression. In this brief overview, evidences are presented that retrovirus-like particles can regularly be demonstrated in human teratocarcinomas cultured in vitro. These viruses are morphologically reminiscent of animal retrovirus strains but show also unique structural features. The viruses possess endogenous reverse transcriptase activity and can be banded at 1.16 g/ml in sucrose gradients, a density characteristic of retroviruses. They can clearly be distinguished from animal retrovirus strains on immunological grounds. We will also briefly summarize the data accumulating for the human T-cell lymphoma viruses (HTLV) which were recently discovered first by Gallo et al. and independently by Hinuma and Miyoshi. HTLV seem to play an etiological role in the establishment of human adult T-cell leukemia/lymphoma and thus represent the first pathogenic human retroviruses.
Insights
Retrovirus-like particles found in human teratocarcinomas exhibit unique features and reverse transcriptase activity. Human T-cell lymphoma viruses (HTLV) are identified as pathogenic, linked to adult T-cell leukemia/lymphoma.
Area of Science:
- Virology
- Molecular Biology
- Oncology
Background:
- Retroviruses have been studied for their role in tumorigenesis and as tools for understanding eukaryotic gene expression.
- Retrovirus-like particles have been observed in human teratocarcinomas cultured in vitro.
Purpose of the Study:
- To present evidence of retrovirus-like particles in human teratocarcinomas.
- To characterize these particles and compare them to known animal retroviruses.
- To summarize data on human T-cell lymphoma viruses (HTLV) and their pathogenic role.
Main Methods:
- Morphological analysis of retrovirus-like particles.
- Biochemical assays for reverse transcriptase activity.
- Sucrose gradient centrifugation to determine particle density.
- Immunological assays for distinguishing viral strains.
Main Results:
- Retrovirus-like particles in human teratocarcinomas are morphologically similar to animal retroviruses but possess unique structural features.
- These particles exhibit endogenous reverse transcriptase activity and a density of 1.16 g/ml, characteristic of retroviruses.
- Immunological analysis distinguishes these particles from animal retrovirus strains.
- Human T-cell lymphoma viruses (HTLV) are implicated in the etiology of human adult T-cell leukemia/lymphoma.
Conclusions:
- Human teratocarcinomas harbor retrovirus-like particles with distinct characteristics.
- HTLV represents the first identified pathogenic human retroviruses, linked to specific leukemias/lymphomas.