FIG 4.

Conceptual model summarizing the generalized inferred evolutionary pathways for low-pathogenic (LP) H5 avian influenza A viruses (IAVs) detected on commercial poultry farms and in live-bird markets (LBMs) in the United States and Canada during 2001 to 2017. H5 viruses introduced by wild waterfowl were inferred to circulate for a longer time in LBMs than on commercial poultry farms. Furthermore, we found evidence suggesting reassortment between H5 viruses and other influenza A viruses in LBMs, resulting in multiple genotypes associated with a single introduction event. The blue and red lines denote genetically distinct gene segments; in each virus, the segments were vertically sorted in the order of PB2, PB1, PA, HA, NP, NA, MP, and NS.