West Nile Virus spread in Europe - 1 phylogeographic pattern analysis and key 2 drivers 3

30 Spread and emergence of West Nile virus (WNV) in Europe have been very different from 31 those observed in North America. Here, we describe key drivers by combining viral genome 32 sequences with epidemiological data and possible factors of spread into phylodynamic models. 33 WNV in Europe has greater lineage diversity than other regions of the world, suggesting 34 repeated introductions and local amplification. Among the six lineages found in Europe, WNV- 35 2a is predominant, has spread to at least 14 countries and evolved into two major co-circulating 36 clusters (A and B). Both of these seem to originate from regions of Central Europe. Viruses of 37 Cluster A emerged earlier and have spread towards the west of Europe with higher genetic 38 diversity. Amongst multiple drivers, high agriculture activities were associated with both 39 spread direction and velocity. Our study suggests future surveillance activities should be 40 strengthened in Central Europe and Southeast European countries, and enhanced monitoring 41 should be targeted to areas with high agriculture activities.