Molecular Dating in the Evolution of Vertebrate Poxviruses

Objectives: The goal of this work was to study the evolutionary history of the vertebrate poxviruses using the Bayesian relaxed clock and a large set of highly conserved vitally important viral genes. Methods: Phylogenetic analysis was performed by the maximum likelihood method using the Paup program. The dating method of Bayes, realized in the Multidivtime, was made. Results: The rate of poxviral evolution is estimated as 0.5–7 × 10 –6 nucleotide substitutions per site per year. We inferred that the modern viruses of the genus Avipoxvirus diverged from the ancestor nearly 249 ± 69 thousand years ago (Tya). The progenitor of the genus Orthopoxvirus separated approximately 166 ± 43 Tya. The separation of the forebear of the genus Leporipoxvirus took place about 137 ± 35 Tya. The next to diverge was the ancestor of the genus Yatapoxvirus. The progenitor of Capripoxvirus and Suipoxvirus diverged 111 ± 29 Tya. Conclusion: The evolutionary analysis based on the historical data and utilizing the Bayesian relaxed clock allowed us to determine the molecular evolution rates of the AT-rich genomes of the vertebrate poxviruses and assess the times of their emergences. Involvement of a large set of the conserved genes controlled by stabilizing selection allowed us to perform molecular dating of the vertebrate poxvirus history.