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Molecular evolution of viruses; 'trees', 'clocks' and 'modules'.
1Research School of Biological Sciences, Australian National University, Canberra, A.C.T.
Journal of Cell Science. Supplement
|January 1, 1987
Summary
Viral genome comparisons confirm traditional classifications and reveal unexpected gene homologies, suggesting modular origins for ancient viruses. Evolutionary studies rely on comparing existing viral forms due to the absence of viral fossils.
Area of Science:
- Virology
- Molecular Biology
- Evolutionary Biology
Background:
- Traditional virus classification relies on observed characteristics.
- Genomic sequencing and structural analysis offer deeper insights into viral relationships.
Purpose of the Study:
- To investigate viral evolution and origins using comparative genomic and structural analyses.
- To explore unexpected genetic relationships between different virus groups.
Main Methods:
- Comparative analysis of viral genome nucleotide and amino acid sequences.
- Examination of three-dimensional structures of viral particle proteins.
- Phylogenetic analysis using sequence differences.
- Inference of ancestral viral properties through isolate comparisons.
Main Results:
- Nucleotide and amino acid sequence comparisons largely support traditional viral taxonomy.
- Unexpected homologies were found between genes of unrelated virus groups and between viral and non-viral genes.
- Structural comparisons revealed surprising relationships, suggesting modular origins for some ancestral viruses.
- Viral gene 'molecular clocks' show inconsistent rates over different evolutionary timescales.
Conclusions:
- Comparative sequence and structural analyses provide crucial insights into viral origins and evolution.
- The concept of modular origins for ancestral viruses is supported by molecular data.
- Understanding viral evolution requires careful consideration of molecular clock inconsistencies and comparative studies of extant viruses.