1. Phylogenetic examination of pandemic H1 HA
Phylogenetic examination of pandemic H1 HA. Each phylogenetic branch and corresponding dot are colored according to their season (1 October to 30 March) and by calculated ΔΔG cluster (see Materials and Methods).
Phylogenetic examination of pandemic H1 HA. Each phylogenetic branch and corresponding dot are colored according to their season (1 October to 30 March) and by calculated ΔΔG cluster (see Materials and Methods). (A) Maximum likelihood phylogeny of HA genes of 2,874 nonduplicate pdmH1N1 IAVs. (B to F) Graphs of estimated change in thermal stability of each HA as related to A/California/7/2009 HA over time. Each dot represents a unique HA sequence. Overlaid lines connect most likely ancestors (MLA) of each HA from the specified year back through time. Each line reflects the calculated lowest genetic difference (highest relatedness) between HA sequences from two seasons. Multiple lines were drawn for ties. Once the MLAs for the rightmost sequences were identified, these were the starting sequences for estimating the MLAs in the next prior season. This analysis was continued until the 2009 season for each starting season. In each season, fewer viruses were identified as being more closely related from the prior season, suggesting that there were genetic bottlenecks from one season to the next.
Eili Y. Klein et al. mSphere 2018; doi: /mSphereDirect