I n this retrospective hepatitis C virus (HCV) study (which has been registered at ClinicalTrials.gov under registration no. NCT00979979.), the Versant LiPA HCV 2.0 (V-LiPA-2) (1-5), the Abbott RealTime HCV GT II assay (Abbott-RT-HCV) (6, 7), and sequencing of the 5= untranslated region (UTR) and NS5B genes were used to genotype 225 samples from patients with HCV monoinfection and HCV-HBV or HCV-HIV dual infection.Reverse transcription, PCR amplification, and sequencing were performed with the ABI BigDye Terminator kit (see Table S1 in the supplemental material), and the samples were analyzed with the ABI 7900HT sequence detection system (Applied Biosystems, Life Technologies Corporation, Grand Island, NY). Sequence analysis was done with Seqscape, and genotypes were assigned by referring to GenBank and then subsequently confirmed by comparing the data with the Los Alamos database and by the generation of a phylogenetic tree by using the Phylogeny Inference Package (8). The V-LiPA-2 assay (Siemens Healthcare Diagnostics) was performed according to the manufacturer's instructions (2). The Abbott m2000sp system, which uses magnetic microparticles and automated sample preparation, was employed (9). Overall, the limit of detection is 500 IU/ml for Abbott-RT-HCV and 1,100 IU/ml for V-LiPA-2. The sensitivity of direct sequencing varies between laboratories. The cost of using Abbott-RT-HCV is about 42% less than that of using V-LiPA-2, and the time required to complete detection with Abbott-RT-HCV is also shorter than when either V-LiPA-2 or direct sequencing is used (Table 1).One hundred seventy-three males (67.8%) and 82 females (32.2%), with a median age of 51 (range, 20 to 79) years, were recruited. The median aspartate aminotransferase level was 76 (range, 18 to 448) IU/liter, and the median alanine aminotransferase level was 133 (range, 14 to 783) IU/liter. The mean HCV load was 6.59 (median, 5.99; range, 2.87 to 7.81) log 10 IU/ml.The V-LiPA-2 had a concordance rate (CR) of 99.2% for genotyping and 96.1% for subtyping. The CRs for genotypes 1, 2, 3, and 6 were Ͼ90%, and the CRs for subtypes 1a/1b, 2a/2b/2c, 3a, and 6a/6b were all Ͼ96% (Table 2). V-LiPA-2 misinterpreted five HCV-1 patients (one 1a as 1b, one 1aϩ1b as 1b, and three 1b as 1a). Two patients with subtype 2aϩ2c were misinterpreted as 2a, and one subtype 2b was misinterpreted as 1b by direct sequencing. V-LiPA-2 misinterpreted one subtype 6a as subtype 1b.The Abbott-RT-HCV had a CR of 99.6% for genotyping, and the CRs for genotypes 1, 2, 3, and 6 were Ͼ99% and that for subtype 1a/1b was 96.1% (Table 2). One case of discordance was a subtype 1b specimen with a light viral load (744 IU/ml), which could not be typed by Abbott-RT-HCV but was accurately subtyped as 1b by V-LiPA-2. One patient with a mixed subtype 1aϩ1b infection (viral load, 62,000 IU/ml) was interpreted as genotype 1 by Abbott-RT-HCV and as subtype 1b by V-LiPA-2. Two patients infected with subtype 1b (viral loads, 4,720 and 33,000 IU/ml) could not be subtyped by Abbott-RT-HCV but were be ...