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Poxvirus genome evolution by gene gain and loss
Austin L Hughes1, Robert Friedman
1Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA. austin@biol.sc.edu
Molecular Phylogenetics and Evolution
|March 2, 2005
Summary
Poxviruses evolve by gaining and losing genes, frequently acquiring host genes through horizontal gene transfer (HGT). This gene capture aids poxvirus adaptation against host antiviral defenses.
Area of Science:
- Virology
- Evolutionary Biology
- Genomics
Background:
- Poxviruses (Poxviridae) are large viruses with double-stranded DNA genomes, encoding over 200 genes.
- Understanding poxvirus evolution involves analyzing gene gain and loss patterns.
Purpose of the Study:
- To investigate gene gain and loss dynamics in poxvirus evolutionary history.
- To identify instances and significance of horizontal gene transfer (HGT) in poxvirus genomes.
Main Methods:
- Phylogenetic analysis based on gene family presence/absence across 17 poxvirus genomes.
- Comparison with phylogenies derived from conserved single-copy genes.
- Identification of gene families shared between poxviruses and animal hosts, indicative of HGT.
Main Results:
- Phylogenetic analysis of gene presence/absence correlated well with sequence-based phylogenies.
- Gene duplications were largely lineage-specific.
- 47% of 34 shared gene families showed evidence of recent HGT from host to virus.
- HGT-acquired genes included those involved in immune evasion (e.g., MHC class I, interleukins) and oxidative stress resistance.
Conclusions:
- Horizontal gene transfer is a recurrent mechanism in poxvirus evolution.
- The acquisition of host genes via HGT is crucial for poxvirus adaptation and overcoming host antiviral responses.