When responses to questions about sexual or personal grooming practices were discordant between partners, responses were recoded for presence rather than absence of the practice. The study was approved
by the Institutional Review Boards of the University of California at San Francisco, Blood Centers of the Pacific, California Pacific Medical Center, Kaiser Permanente Northern California, St. Louis University, and the Centers for Disease Control and Prevention. Serum samples from index subjects were tested for anti-HCV via enzyme immunoassay (EIA 2.0) (Abbott Small molecule library Laboratories, Abbott Park, IL) and for HCV RNA via qualitative polymerase chain reaction (PCR) with detection limit ≤50 IU/mL (Roche Amplicor, Roche Molecular Diagnostics, Pleasanton, CA) (if not documented in medical records in prior 6 months). Serum samples from partners
were tested for anti-HCV via EIA and positive results confirmed via recombinant immunoblot assay (RIBA 3.0, Chiron Corporation, Emeryville, CA). RIBA-positive samples were tested for HCV RNA via qualitative PCR. Serotyping of the antibody based on RIBA methodology was used in anti–HCV-positive Mitomycin C in vivo concordant couples with HCV RNA–negative partners.10 Genotype was determined in samples from anti–HCV-positive, HCV RNA–positive concordant couples using the InnoLipa assay (Innogenetics, Ghent, Belgium). HCV RNA–positive specimens from genotype-concordant couples were amplified via reverse-transcription nested PCR, and the HCV consensus sequences were determined by directly sequencing uncloned PCR products
from the 897-nucleotide-long NS5B region for genotype 1a and 1b samples and from a 944-nucleotide-long NS5B region for the 2b samples employing ABI dye-termination techniques.11 The 1a and 1b sequences correspond to H77 positions 7479 to 8375 (with genotype 1b sequences missing three nucleotides relative MCE to the 1a sequences, resulting in a gap corresponding to 7566 to 7568 in the H77 sequence). These 1a/1b alignments cover the region of the ORF coding for the last 42 amino acids of NS5A and the first 258 amino acids of NS5B.The genotype 2b alignments correspond to the H77 sequence 8326-9269, encoding NS5B from amino acid 242 to 556.To evaluate the relatedness between isolates from genotype-concordant partners, the consensus sequences from their isolates were compared with corresponding regions from reference sequences of the same subtype downloaded from the Broad Institute or from the National Center for Biotechnology Information; this included 99 genotype 1a and 97 genotype 1b sequences. The sequences were imported into the MEGA 4 sequence analysis package, and the pairwise distances and number of differences were calculated for each pair. These nucleotide sequences have been submitted to GenBank under accession numbers HQ022864-HQ022879.