title: Mutations to the probe of Cobas TaqMan HIV-1 ver. 1.0 assay causing undetectable viral load in a patient with acute HIV-1 infection.
abstract: We encountered a human immunodeficiency virus (HIV)-1 in which the viral load was undetectable with the Cobas TaqMan HIV-1 ver. 1.0 (CTM v.1.0) in a patient with acute HIV-1 infection. The CTM v.1.0 assay showed more than 1,000-fold underestimation compared with the subsequent Cobas Amplicor Monitor v.1.5 assay. Because five mismatches to the CTM v.1.0 assay probe in the HIV-1 virus in the patient were disclosed by the manufacturer, partial gag regions of the HIV genome were directly sequenced from the patient's plasma viral RNA. The detected single nucleotide point mutations were located near the 5'-end of the Cobas Amplicor Monitor probe. Clinicians should be very careful in making interpretations when indeterminate Western blot analysis results and a low or even undetectable HIV-1 viral load are encountered with the CTM HIV-1 ver. 1.0 assay in patients with suspected acute HIV infection. Repeating Western blot analysis is essential before considering a low HIV-1 viral load to be a false-positive result.
authors.affiliation: Department of Laboratory Medicine, Tokyo Medical University Hospital, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan. mhk@tokyo-med.ac.jp
authors.forename: Mihoko
authors.initials: M
authors.lastname: Yotsumoto
authors.forename: Keiko
authors.initials: K
authors.lastname: Shinozawa
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Wataru
authors.initials: W
authors.lastname: Sugiura
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Miura
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Fukutake
mesh_terms: D000328:Adult; D001483:Base Sequence; D015153:Blotting, Western; D005188:False Negative Reactions; D015658:HIV Infections / Q000175:diagnosis / Q000821:virology*; D015497:HIV-1 / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D016133:Polymerase Chain Reaction / Q000379:methods; D012680:Sensitivity and Specificity; D019562:Viral Load / Q000379:methods / Q000592:standards