An official website of the United States government
Here's how you know
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 tree from 487 nucleotides of V3-V4 env alignment. The tree was inferred as described in the legend to Fig. 1. The symbols used in this figure represent different regions and treatment statuses as depicted in Fig. 1.