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Compositional bimodality and evolution of retroviral genomes
S Zoubak1, A Rynditch, G Bernardi
1Laboratoire de Génétique Moléculaire, Institut Jacques Monod, Paris, France.
Gene
|October 1, 1992
Summary
Retroviral genomes in warm-blooded vertebrates exhibit two distinct compositional classes: GC-rich and GC-poor. This bimodality, alongside genomic homogeneity, suggests evolution within integrated host genomes.
Area of Science:
- Virology
- Genomics
- Molecular Evolution
Background:
- Retroviral genomes display diverse compositional patterns.
- Understanding these patterns is key to retroviral evolution and host-pathogen interactions.
Purpose of the Study:
- To characterize the compositional distribution of retroviral genomes, genes, and long terminal repeats in warm-blooded vertebrates.
- To investigate the relationship between retroviral genome composition and their integration sites within host genomes.
Main Methods:
- Analysis of genomic composition (GC content) for retroviral genomes, genes (third codon positions), and long terminal repeats.
- Classification of retroviruses into GC-rich and GC-poor groups.
- Comparison of viral genome composition with host genome isochores.
Main Results:
- Retroviral genomes show a striking bimodal compositional distribution (GC-rich vs. GC-poor).
- Within each retroviral genome, composition is remarkably homogeneous.
- GC-rich retroviruses (e.g., oncoviruses) integrate into GC-rich host isochores.
- GC-poor retroviruses (e.g., lentiviruses, spumaviruses, some oncoviruses) integrate into GC-poor host isochores.
Conclusions:
- The compositional bimodality of retroviral genomes likely results from their evolutionary adaptation within integrated host genomic environments.
- Retroviral genome composition is conserved and reflects specific integration preferences within host DNA.