DNA sequencing of env genes was carried out by Lone Star Labs, Inc. (Houston, TX) utilizing the ABI Prism H Automated DNA sequencer 377XL and Big Dye TM Terminator Ready Reaction Cycle Sequencing Kit. Nucleotide sequences were edited and assembled using Sequencher v4.7, translated using Se-Al v2.0all, and nucleotide or amino acid alignments were created using Clustal W v1.83. Neighbor joining phylogenetic trees were generated by Clustal W v1.83 using gap-stripped nucleotide sequences of the complete env gene, and reliability of branching orders was assessed by bootstrap analysis using 1,000 replicates. Trees were visualized using NJ Plot. Aligned sequences were imported into the Highlighter tool to analyze viral diversity (http://www.hiv.lanl.gov/content/ sequence/HIGHLIGHT/highlighter.html). Sequences have been deposited into Genbank under the accession numbers GQ485312-GQ485447.