FIG 1.

Vpu sequence diversity. (A) Maximum-likelihood phylogeny inferred from a nucleic acid sequence alignment of 300 HIV subtype A, B, C, and D vpu isolates analyzed in this study (32 vpu sequences encoding viral recombinants or other subtypes are not shown). Scale in estimated nucleotide substitutions per site. (B) Gap-stripped alignment of the Vpu consensus amino acid sequences for subtypes A, B, C, and D (defined as the most frequently observed residue at each position in our study sequences). Colors match the phylogeny in panel A. The inverted blue triangle denotes a common insertion that occurred exclusively in subtype C, usually seven amino acids in length (usually LA[K/R]VDYR). Major Vpu structural features are highlighted. β-TrCP, beta-transducin repeat-containing protein.