Bayesian phylodynamics of avian influenza A virus H9N2 in Asia with time-dependent predictors of migration
Fig 2
Time scaled phylogenetic trees of H9N2 influenza viruses in Asia.
(a) estimated using DTA model and (b) using MASCOT model. The colour of tree branches indicates location (see legend) with the maximum probability. A colour change on a branch indicates a virus migration event. Numbers on branches represent posterior probability of displayed location. Numbers in parentheses represent 95% highest posterior density interval of divergence time of the nearest node. A black asterisk represents a virus sequence isolated from wild bird. UAE is short for the United Arab Emirates. Both methods place the origin of H9N2 in Hong Kong, from where it spread to East Asia. This is likely driven by a lack of samples from other locations in the 1970s and 80s. DTA and MASCOT differ in the details on how it spread to West and South Asia. Bars on the right indicate three established lineages based on the phylogenetic relationship between the virus and the representative strains in Asia. The phylogenetic cluster of isolates from domestic poultry in nearby regions indicates their roles in virus spread among neighbouring locations; whereas the dispersal distribution of isolates from wild birds on the phylogeny questions their roles in virus spread across countries and genetic groups.