Conditioning these metrics over all QC-passed trees revealed a mean root date of December 1995 (95% HPD, from August 1995 to March 1996), consistent with the participant’s clinically estimated infection date, and a mean env-gp120 evolutionary rate of 4.8 × 10−5 (95% HPD 3.8 × 10−5 – 6.0 × 10−5) substitutions per nucleotide site per day (Table S1). The gene discussed is ERVW-1; the disease is infection.