Figure 1.

Maximum-likelihood phylogenetic tree, constructed with HIV-1 partial pol sequences from 59 study subjects (76 sequences) and 335 reference sequences, identified through a BLAST search of the LANL HIV database. Reference tips are labeled with LANL accession numbers. Clades involving only LANL references are collapsed for display purposes. Study sequences are labeled in black (acute index cases) and blue (partners). Individual persons are shown with shapes at tips: the circles are men and squares are women. The numbers at the tips are dates of sampling (month, year). Dyads are labeled as 1–13. Bootstrap support is labeled at clades involving study sequences. Abbreviations: HIV, human immunodeficiency virus; LANL, Los Alamos National Laboratory.