Phylogenetic tree containing all available NS1 sequences, assembled by
following the neighbor joining (NJ) method and using p distances. Selected NS1
sequences used in this study are depicted as colored arrows along the tree based
on their host origin: human (red), avian (blue), swine (green), and other
mammals (gray). The distance bar is shown below the tree. Strains are depicted
as shown in Table S1.
Asterisks denote isolates that were involved in cross-species transmissions
following this order: Vietnam/1203/2004 (H5N1) and A/Shanghai/02/2013 (H7N9)
viruses were included as avian origin (blue arrows), because they came from a
zoonotic transmission from an avian host. Similarly, A/Elephant
seal/California/2010 is red (human), because it was a reverse zoonotic
transmission from humans.