| Participant: | Schuh, Amy |
THE RATE AND TIME-FRAME OF JAPANESE ENCEPHALITIS VIRUS EVOLUTION
Amy J. Schuh1,2,3,4, L. Li, B.S. 1,2,3,4, R. B. Tesh, M.D. 1,2,3,4, B.L. Innis, M.D. 5,6, and A.D.T. Barrett, Ph.D. 1,2,3,4
1Department of Pathology, 2Center for Biodefense and Emerging Infectious Diseases, 3Sealy Center for Vaccine Development, and 4Institute for Human Infections and Immunity, UTMB; 5Current affiliation: GlaxoSmithKline Biologicals, King of Prussia, PA;, 6Former affiliation: Department of Virus Diseases, Walter Reed Army Institute of Research, Washington, DC
Background: Previous studies by our lab suggest that Japanese encephalitis virus (JEV) originated in the Indonesia-Malaysia region and evolved there into at least four genotypes (GI-IV); GIV, the most divergent genotype, remained confined to the Indonesia-Malaysia region, whereas GI-III, the most recent genotypes, spread throughout Asia. However, the time scale by which GI-III of JEV diverged from the most recent common ancestor (MRCA) and the rate of molecular evolution of these three virus genotypes with distinct epidemiological histories remains unclear. Methods: To conduct our analyses, we examined the nucleotide sequence of the entire protein coding region of 31 JEV isolates retrieved from GenBank and 2 novel virus isolates collected between 1935 and 2007. The rate of evolution according to virus genotype was calculated, as well as the times of the MRCA of the virus genotypes using a Bayesian Markov Chain Monte Carlo method (MCMC). Results: Subsequent to the divergence of GIV of JEV, the MRCA of GI-III diverged followed by the MRCA of GI and GII, the MRCA of GIII, the MRCA of GII, and lastly the MRCA of GI. Additionally, GI-III of the virus exhibited different rates of molecular evolution. Conclusions: Information about the rate and timing of JEV evolution provides not only information about the virus’ epidemiological history, but also is fundamental to understanding the processes controlling evolution and emergence of JEV.
Funding: This work was supported in part by NIH grant AI 067847.