| Budget Amount *help |
¥17,810,000 (Direct Cost: ¥13,700,000、Indirect Cost: ¥4,110,000)
Fiscal Year 2015: ¥5,460,000 (Direct Cost: ¥4,200,000、Indirect Cost: ¥1,260,000)
Fiscal Year 2014: ¥5,850,000 (Direct Cost: ¥4,500,000、Indirect Cost: ¥1,350,000)
Fiscal Year 2013: ¥6,500,000 (Direct Cost: ¥5,000,000、Indirect Cost: ¥1,500,000)
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| Outline of Final Research Achievements |
Human influenza viruses are known to escape continuously from host immune defense by accumulating mutations on hemagglutinin. A recent multivariate statistic technique has extracted their surprisingly simple evolutionary trajectories on a low dimensional projected trait spaces. Here I propose a simple Bayesian update model to reproduce such evolutionary trends.
In the model, a mutant that will cause epidemic in the next year is chosen randomly according the its probability of being generated by the parental strain, multiplied by its fitness determined by the past past infection history and accumulation of host herd immunity.
This model generates nearly linear trends in the series of epidemic strains placed on antigen space with a randomly chosen direction. The angles made by consecutive axes of annual antigenic changes are narrowly distributed around 0, and the distance between epidemic strains has a peaky distribution around the characteristic width of cross-immunity.
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