Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Phylogenetic trees for human and swine influenza virus M1 and NP. Shown are maximum clade credibility trees for NP and M1. The swine influenza virus lineage is in blue, and the human influenza virus lineage is in red. The dark blue and red lines represent the trunk. The dotted black lines indicate that human and swine influenza virus lineages share a recent common ancestor (estimated times to the most recent common ancestor are 13 and 6 years for M1 and NP, respectively).
